Econstudentlog

Richard Feynman: Fun to Imagine | Using physics to explain how the world works

This is great stuff:

February 24, 2013 Posted by | Physics, science | Leave a comment

A few crime data

“Key Figures – Denmark: Among 35 year old men in 2004: 28% convicted at least once (non-trafic), 14% convicted at least twice (non-trafic), 12% prison sentence (suspended or not).”

From a course lecture note. I’ve written about the crime rates of immigrants in Denmark before (Danish link). The number you need to know from that article is this one: In 2007, 27,2% of (n=1449) male descendants of non-Western immigrants at the age of 20-29 years old got a conviction. I will emphasize that this is in that year alone; this is not an estimate of how many of the 30 year-olds got convicted while they were at the age of 20-29 – this is a snapshot, and during one year more than a fourth of these people got convicted of a crime.

You’d be tempted to say that the fraction of non-Western descendants in Denmark that commit crime while at the age of 20-29 corresponds to the fraction of Danes at the age of 35 who’ve ever been convicted. It’s not quite that bad, because the descendant numbers include traffic violations which are excluded in the other measure and traffic crimes make up a large chunk of the total – 58% of convictions of all descendants (Statistics Denmark doesn’t make it easy to separate non-Westerners from the rest) were traffic-related in 2011 (STRAFNA1). It’s noteworthy that the proportion of all crimes which are traffic-related when using this data at least seems to be significantly higher for ethnic Danes than it is for descendants; for persons of Danish ethnic origin 67% of all convictions were traffic-related (STRAFNA1). If we trust the 58% estimate above, roughly 16% of non-Westerners got a non-traffic conviction in 2008. Note that numbers vary across sources; this measure gives 117.517 traffic law convictions out of 200.091 total convictions, which corresponds to ~59% – I don’t have a good explanation for why the sources differ here. Using the numbers from StrafNA1 only gives you 102.265 traffic law convictions in total, 14575 (7%) of which were committed by immigrants or descendants (who make up 10,1% of the population).

Of course one might argue that the ‘key figures’ above include descendants and immigrants at the age of 35 as well – but I don’t think using it as an ‘ethnic Danes’ ballpark estimate is too problematic, it’s the best I’ve got anyway. So while the fraction of non-Western descendants in Denmark at the age of 20-29 who get convicted of a crime during any given year doesn’t exactly correspond to the fraction of Danes at the age of 35 who’ve ever been convicted, it probably does correspond to more than half (~57% – ~16/28).

The ‘key figures’ for 35 year olds also included a recidivism measure; half of those convicted during their first 35 years of life got at least one more conviction. Note that if you want the hypothetical proportion of repeat offenders in the descendants group at the age of 35 to be similar to the Danish total, the number of repeat offenders in the 27,2%/~16% (year by year) group would have to be very low and the number of total convicts would have to be very high. According to this article (Danish), ‘for ordinary criminals the recidivism rate is 30 % within 2 years of release’ (“For almindelige kriminelle er tilbagefaldsprocenten på 30 procent inden for to år efter løsladelsen.”). My brief look at Statistikbanken didn’t give me any numbers on recidivism rates (the menu here is blank), and I’m not sure it’s a good idea to use this estimate in calculations here because the use of the word ‘release’ likely means that the people included in this measure served time – and most convictions do not lead to jail time (..and the recidivism rate for a previous jail convict is likely different from the recidivism rate of a person who has not served jail-time). I’m lazy and it’s probably not a good estimate to use so I won’t model or do a lot of number crunching on this stuff. However it’s safe to say from the data that either a huge number of non-Western descendants will end up having been convicted of a crime, or a quite big number of them commit a huge amount of crime each. Unless you assume a high recidivism rate it’s also safe to say that the proportion of criminals grows pretty damn fast with crime rates like that (even though the growth rate falls ‘over time’). There certainly isn’t far from 16% to 28% when you add a significant amount to the first number each period and you have a lot of periods in which to add more stuff.

Update: The numbers in this recent (Danish) publication on recidivism rates seem relevant. It confirms my suspicion that the group of people who’ve been released from jail after having served their time have quite high recidivism rates (60%) compared to other groups. On average offenders with only ‘grundskole’ (1st-9th grade), the educational grouping with the by far highest average recidivism rate, had a recidivism rate of 44%. Via that link I also came across this publication from Statistics Denmark which may be of interest – there’s a lot of data here. They haven’t written the stuff in English, but they have added English translations of key concepts at the end of the publication so that it should theoretically be possible to read the tables if you’re patient.

As to the original remark that: ‘There certainly isn’t far from 16% to 28% when you add a significant amount to the first number each period and you have a lot of periods in which to add more stuff,’ note that if we assume that the two-year descendant recidivism rate is 50% and that the traffic crime proportion estimate is correct so that ~16% of the male descendants at the age of 20-29 got a non-traffic conviction during 2008, then the proportion of descendants with a conviction after two years is 0.16 +(1-0,5)*0.16 = 24%. A 50% recidivism rate is higher than the average recidivism rate of the lowest educated group in the publication linked to above. As I said, there isn’t far from 16% to 28%.

February 24, 2013 Posted by | data, demographics, immigration | Leave a comment

Causal Models – How People Think about the World and Its Alternatives

by Steven Sloman.

I’ve been very busy lately due to the new semester starting and my exam this week. Today was to be different; I had lectures in the morning, but the rest of the day (or at least a significant part of it…) I’d decided to spend in the company of a book of my choosing. Sloman’s book was the one I picked.

I finished it not long ago – it’s not very long, only 181 pages excluding notes and references, and it’s definitely a book you can finish in one day/sitting if you want to.

But whether you want to or not is a different matter – I don’t think the book is very good and I don’t recommend it. If I was reviewing it on amazon, I’d give it either two stars or three.

“An experiment requires manipulation. Some variable, some potential cause (often called an independent variable), is chosen along with another variable, a potential effect (often called a dependent variable). The cause is then manipulated by setting it to two or more values and the effect is measured. If the value of the effect differs for different values of the cause, then we can infer that the cause has some influence on the effect; a causal relation exists.”

A quote from the book. At least some places, that’s the level we’re at. This kind of stuff – and stuff like how to calculate a marginal or conditional probability – is not stuff I need to read and it’s not stuff I’m going to spend a lot of time on.

Another quote, this one from the introduction:

“Chapters 4 and 5 provide the technical meat of the book; chapter 4 is about causal models generally, and chapter 5 is about the representation of intervention. Although I’ve tried to keep these chapters as light as possible, too light for more mathematically sophisticated readers…”

And to that I’d say: Yeah, ‘too light’ indeed. And if the ‘meaty’ chapters were too light…

It could have been a good book. There was some new, interesting stuff in there.

But there wasn’t enough of it. And if I had to read only one book about this stuff, I’m sure this wouldn’t be the one to read.

February 22, 2013 Posted by | books, philosophy | Leave a comment

An update

I haven’t posted much here over the last couple of days because of ‘work’ – I had an exam today. I passed.

None of these questions were asked:

Naturally I’ve done some thinking about exam-stuff over the last few days, some of which I was thinking about blogging. Anyway I won’t blog it now – I’ve not slept very well or very much, and I have lectures this afternoon.

February 20, 2013 Posted by | personal | Leave a comment

More preliminary data on the blood glucose/mental performance ‘study’

Previous posts here and here. I haven’t been very good at gathering data and during the exam period I basically stopped, but I do have 105 observations at this point.

The R-squared and the estimated effect size in a simple linear model both look almost identical at this point in time as they did 55 observations ago – I’ve posted both the old scatterplot (first) and an updated version (second) below – click to view the full size versions:

Scatter

105 obs

I have however been a little suspicious about a few data-points which were collected around the time of the London Chess Classics tournament last year – I spent a significant amount of time on chess during that week and my playing strength when playing blitz games went up a lot those days too (I gained ~150 elo points over 4-5 days, which is a lot – I’ve lost that rating again at this point). Here’s what the image looks like without those observations:

without London days

I am not convinced that ‘blood glucose has no effect on tactics trainer performance’ is the conclusion to draw from this data-set, so I’m still collecting data at this point. The true data generating process of course includes many variables not included above – you may want to reread the first article if you want to know more about the ‘true’ DTG.

I wrote in my first post that: “I know myself well enough to know that I don’t want to bother with non-linear models when I look at this stuff later; it’s a poor and underspecified model to begin with.” If I actually have to work with methods which prove useful when analysing this type of dataset during my statistics course this semester (do remember that I have not included all the data I’ve gathered in the above plots), I may change my mind about how much work I’ll do on this dataset. Maybe I’ll be reminded of useful ways to handle stuff like this during the course; stuff that I’ve forgotten about at this point. We’ll see how it goes.

If anyone else would like to have a look at the data, just leave a comment below – I’d be happy to send you a copy of the data.

February 16, 2013 Posted by | data, diabetes, personal | Leave a comment

Wikipedia articles of interest

i. Coelacanth.

Coelacanth (pron.: /ˈsləkænθ/) is a rare order of fish that includes two extant species: West Indian Ocean coelacanth (Latimeria chalumnae) and the Indonesian coelacanth (Latimeria menadoensis). They follow the oldest known living lineage of Sarcopterygii (lobe-finned fish and tetrapods), which means they are more closely related to lungfish, reptiles and mammals than to the common ray-finned fishes. They are found along the coastlines of the Indian Ocean and Indonesia.[1][2] Since there are only two species of coelacanth and both are threatened, it is the most endangered order of animals in the world. The West Indian Ocean coelacanth is a critically endangered species.

Coelacanths belong to the subclass Actinistia, a group of lobed-finned fish that are related to lungfish and certain extinct Devonian fish such as osteolepiforms, porolepiforms, rhizodonts, and Panderichthys.[3] Coelacanths were thought to have gone extinct in the Late Cretaceous, but were rediscovered in 1938 off the coast of South Africa.[4] The coelacanth is considered a “living fossil” due to its apparent lack of significant evolution over the past millions of years.[3] The coelacanth is thought to have evolved into roughly its current form approximately 400 million years ago.[5]

800px-Latimeria_Chalumnae_-_Coelacanth_-_NHMW

ii. Continued fraction.

iii. Progeria.

Progeria (also known as “Hutchinson–Gilford (Progeria) Syndrome“,[1][2] and “Progeria syndrome[2]) is an extremely rare genetic disease wherein symptoms resembling aspects of aging are manifested at an early age. The word progeria comes from the Greek words “pro” (πρό), meaning “before”, and “géras” (γῆρας), meaning “old age”. The disorder has very low incidences and occurs in an estimated 1 per 8 million live births.[3] Those born with progeria typically live to their mid teens and early twenties.[4][5] It is a genetic condition that occurs as a new mutation, and is rarely inherited. Although the term progeria applies strictly speaking to all diseases characterized by premature aging symptoms, and is often used as such, it is often applied specifically in reference to Hutchinson-Gilford Progeria Syndrome (HGPS).

Scientists are particularly interested in progeria because it might reveal clues about the normal process of aging.[6][7][8] Progeria was first described in 1886 by Jonathan Hutchinson.[9] It was also described independently in 1897 by Hastings Gilford.[10] The condition was later named Hutchinson-Gilford Progeria Syndrome (HGPS).”

iv. Dieppe Raid.

“The Dieppe Raid, also known as the Battle of Dieppe, Operation Rutter and, later, Operation Jubilee, was a Second World War Allied attack on the German-occupied port of Dieppe. The raid took place on the northern coast of France on 19 August 1942. The assault began at 5:00 a.m. and by 10:50 a.m. the Allied commanders were forced to call a retreat. Over 6,000 infantrymen, predominantly Canadian, were supported by limited Royal Navy and large Royal Air Force contingents. […]

Objectives included seizing and holding a major port for a short period, both to prove it was possible and to gather intelligence from prisoners and captured materials, including naval intelligence in a hotel in town and a radar installation on the cliffs above it. Although neither were completely successful, some knowledge was gained while assessing the German responses. The Allies also wanted to destroy coastal defences, port structures and all strategic buildings. The raid could have given a morale boost to the troops, Resistance, and general public, while assuring the Soviet Union of the commitment of the United Kingdom and the United States.

No major objectives of the raid were accomplished. A total of 3,623 of the 6,086 men (almost 60%) who made it ashore were either killed, wounded, or captured. The Royal Air Force failed to lure the Luftwaffe into open battle, and lost 96 aircraft (at least 32 to flak or accidents), compared to 48 lost by the Luftwaffe.[2] The Royal Navy lost 33 landing craft and one destroyer.”

So yeah, it didn’t go that well.

v. Obesity in the Pacific. The main figure from the article, click to enlarge:

obesity

In Nauru you’re pretty much a statistical outlier if you’re not overweight. “In the Marshall Islands in 2008 there were 8,000 cases of diabetes in a population of only 53,000.” That’s close to 1 in 6. There’s more data in the related article on Epidemiology of obesity.

vi. Fixed action pattern. Part of the fun of reading this article is derived from the fact that it makes use of an abbreviation which is quite often used, but usually means something else… (An example from the article: “Replicating the releasing mechanism required to trigger a FAP is known as code-breaking.”)

February 13, 2013 Posted by | biology, diabetes, history, mathematics, medicine, wikipedia | Leave a comment

Khan Academy videos of interest

Took me a minute to solve without hints. I had to scribble a few numbers down (like Khan does in the video), but you should be able to handle it without hints. (Actually I think some of the earlier brainteasers on the playlist are harder than this one and that some of the later ones are easier, but it’s a while since I saw the first ones.)


Much more here.

Naturally this is from the computer science section.

It’s been a while since I’ve last been to Khan Academy – it seems that these days they have an entire section about influenza.

February 10, 2013 Posted by | Computer science, Khan Academy, Lectures, mathematics, medicine | Leave a comment

Quotes

i. “”All education is a struggle,” said Marchbanks. “I had to struggle against schools and universities, of course, in order to get time to educate myself, which I did magnificently.”” (Robertson Davies)

ii. “I think a great many marriages would be saved if people would behave toward one another with the same courtesy that they would extend to someone whom they really didn’t know as well as a marriage necessarily implies. … It’s not very easy to do, but it is surely easier to do than to haggle and nag and fight and bitch and yelp at one another as you hear a lot of married people doing … They seem to feel that the familiarity of affection permits anything, including insult.” (-ll-)

iii. “I have known far too many university graduates, in this country and in my own, who, as soon as they have received the diploma which declares them to be of Certified Intelligence, put their brains in cold storage and never use them again until they are hauled away to the mortuary.” (-ll-)

iv. “Any enjoyment or profit we get from life, we get Now; to kill Now is to abridge our own lives.” (-ll-)

v. “To oblige a friend by inflicting an injury on his enemy is often more easy than to confer a benefit on the friend himself.” (Anthony Trollope)

vi. “Many people talk much, and then very many people talk very much more.” (-ll-)

vii. “It is easy for most of us to keep our hands from picking and stealing when picking and stealing plainly lead to prison diet and prison garments. But when silks and satins come of it, and with the silks and satins general respect, the net result of honesty does not seem to be so secure.” (-ll-. See also this.)

viii. “It contributes greatly towards a man’s moral and intellectual health, to be brought into habits of companionship with individuals unlike himself, who care little for his pursuits, and whose sphere and abilities he must go out of himself to appreciate.” (Nathaniel Hawthorne)

ix. “Many writers lay very great stress upon some definite moral purpose, at which they profess to aim their works. […] A high truth, indeed, fairly, finely, and skillfully wrought out, brightening at every step, and crowning the final development of a work of fiction, may add an artistic glory, but is never any truer, and seldom any more evident, at the last page than at the first.” (-ll-)

x. “My ambition is handicapped by my laziness.” (Charles Bukowski)

xi. “Life is not always a matter of holding good cards, but sometimes, playing a poor hand well.” (Jack London)

xii. “Her own limits were the limits of her horizon; but limited minds can recognize limitations only in others. And so she felt that her outlook was very wide indeed, and that where his conflicted with hers marked his limitations; and she dreamed of helping him to see as she saw, of widening his horizon until it was identified with hers.” (-ll-)

xiii. “Isolation is the worst possible counselor.” (Miguel de Unamuno)

xiv. “Good humour may be said to be one of the very best articles of dress one can wear in society.” (William Makepeace Thackeray)

xv. “A man must be himself convinced if he is to convince others. The prophet must be his own disciple, or he will make none. Enthusiasm is contagious: belief creates belief.” (George Henry Lewes)

xvi. “There are many justifications of silence; there can be none of insincerity.” (-ll-)

xvii. “I must say I’m not very fond of oratory that’s so full of energy it hasn’t any room for facts.” (Sinclair Lewis)

xviii. “The best kind of charity is to help those who are willing to help themselves.” (P. T. Barnum)

xix. “Among those points of self-education which take up the form of mental discipline, there is one of great importance, and, moreover, difficult to deal with, because it involves an internal conflict, and equally touches our vanity and our ease. It consists in the tendency to deceive ourselves regarding all we wish for, and the necessity of resistance to these desires.” (Michael Faraday)

xx. “Fate chooses our relatives, we choose our friends.” (Jacques Delille. (Le sort fait les parents, la choix fait les amis.))

February 10, 2013 Posted by | quotes | Leave a comment

Stuff

i. Sample Size in Psychological Research Over the Past 30 Years.

“Summary. —The American Psychological Association (APA) Task Force on Statistical Inference was formed in 1996 in response to a growing body of research demonstrating methodological issues that threatened the credibility of psychological research, and made recommendations to address them. One issue was the small, even dramatically inadequate, size of samples used in studies published by leading journals. The present study assessed the progress made since the Task Force’s final report in 1999. Sample sizes reported in four leading APA journals in 1955, 1977, 1995, and 2006 were compared using nonparametric statistics, while data from the last two waves were fit to a hierarchical generalized linear growth model for more in-depth analysis. Overall, results indicate that the recommendations for increasing sample sizes have not been integrated in core psychological research, although results slightly vary by field. This and other implications are discussed in the context of current methodological critique and practice.”

I unfortunately can’t find an ungated copy of this paper online, but here’s a little more stuff from the paper:

“Cohen (1962) concluded, “Increased sample size is likely to prove the most effective general prescription for improving power” (p. 153), but there is little evidence that the field has taken note. After reviewing the literature, Holmes (1979) reported finding only two studies that examined sample sizes directly. One study reported the number of articles published about single-subject samples (Dukes, 1965), and the other examined sample sizes reported in two British journals, finding that every reported study had N ≤ 25 (Cochrane & Duffy, 1974).
Holmes (1979, 1983) himself examined sample sizes in four APA journals in 1955 and 1977, and reported median sample sizes for the total study and each of the comparison groups. His general conclusions were that sample size had not changed significantly between 1955 and 1977, and that the typical sample size in psychology did not seem large […] the purpose of the present study was to examine sample sizes reported in the same four journals examined by Holmes (1979, 1983), but in more recent volumes. Two additional data collections were undertaken, one in 1995 (about the time the Task Force was formed), and the other in 2006 […]

Table 1(click to view in a higher resolution)

So yeah, the median sample size was 32 in 1995 and 40 in 2006. 25% of published studies had n=14 or less in 1995, and n=18 or less in 2006. The sample size that occured most often in the 1995 sample was n=8; in 2006 it was 16.

“Our modeling showed that sample size depends on the field. Smaller samples are needed in experimental settings, presumably because sufficient control of extraneous variation is in place, and standard errors tend to be smaller. (Higher cost per participant may also be a factor, due to sophisticated measurement equipment or laboratory controls.) However some fields, such as applied and developmental psychology, depend much more on quasi-experimental research because of their greater emphasis on comparisons of naturally occurring groups and ecological validity. Such research designs result in more variation in the data, and larger samples are necessary to gain feasible standard errors. (Lower cost per participant may also be a factor, because of the availability of institutional archival data.) […]

We found that overall, the relatively small sample sizes found by Holmes did not increase significantly over the next 29 years. However, there was significant variability in the change in sample size over time by field, with increases from 1977 to 2006 appearing in the Journal of Abnormal Psychology and Developmental Psychology, and no change in Experimental Psychology or Applied Psychology (which actually showed a slight decrease for individual sample size).
The third hypothesis was that sample sizes remained unchanged after the Task Force report in 1999. A change would have been reflected in a significant difference in sample size between 1995 and 2006, but none was found. This result is not surprising, given previous research on power (e.g., Cohen, 1962; Sedlmeier & Gigerenzer, 1989; Rossi, 1990; Maddock & Rossi, 2001; Maxwell, 2004) and Holmes’ own studies on sample size (Holmes, 1979, 1983; Holmes, et al., 1981). However, it is troubling, especially when one considers the increased use of sophisticated multivariate analyses and statistical modeling techniques during this time that would require the employment of larger sample sizes (Merenda, 2007; Rodgers, 2010).”

Here’s a link to one of the ungated power studies mentioned in the paper.

ii. Old pictures. Lots of old pictures.

iii. BookOs.

iv. “What [would happen] if I took a swim in a typical spent nuclear fuel pool? Would I need to dive to actually experience a fatal amount of radiation? How long could I stay safely at the surface?”

And now you know.

There’s a little background stuff on the subject here.

v. For some reason this picture touched me deeply (click to view full size):

Mongolian_woman_condemned_to_die_of_starvation_(retouched)Via Wikipedia.

vi. “Facebook killed TV.” – from this Paul Graham essay on Why TV Lost.

vii. The End of History Illusion.

“We measured the personalities, values, and preferences of more than 19,000 people who ranged in age from 18 to 68 and asked them to report how much they had changed in the past decade and/or to predict how much they would change in the next decade. Young people, middle-aged people, and older people all believed they had changed a lot in the past but would change relatively little in the future. People, it seems, regard the present as a watershed moment at which they have finally become the person they will be for the rest of their lives. This “end of history illusion” had practical consequences, leading people to overpay for future opportunities to indulge their current preferences.”

Unfortunately I’ve not been able to find an ungated link, but here’s a bit more from the concluding remarks of the paper:

“Across six studies of more than 19,000 participants, we found consistent evidence to indicate that people underestimate how much they will change in the future, and that doing so can lead to suboptimal decisions. Although these data cannot tell us what causes the end of history illusion, two possibilities seem likely. First, most people believe that their personalities are attractive, their values admirable, and their preferences wise (10); and having reached that exalted state, they may be reluctant to entertain the possibility of change. People also like to believe that they know themselves well (11), and the possibility of future change may threaten that belief. In short, people are motivated to think well of themselves and to feel secure in that understanding, and the end of history illusion may help them accomplish these goals.

Second, there is at least one important difference between the cognitive processes that allow people to look forward and backward in time (12). Prospection is a constructive process, retrospection is a reconstructive process, and constructing new things is typically more difficult than reconstructing old ones (13, 14). The reason this matters is that people often draw inferences from the ease with which they can remember or imagine (15, 16). If people find it difficult to imagine the ways in which their traits, values, or preferences will change in the future, they may assume that such changes are unlikely. In short, people may confuse the difficulty of imagining personal change with the unlikelihood of change itself.

Although the magnitude of this end of history illusion in some of our studies was greater for younger people than for older people, it was nonetheless evident at every stage of adult life that we could analyze. Both teenagers and grandparents seem to believe that the pace of personal change has slowed to a crawl and that they have recently become the people they will remain. History, it seems, is always ending today.”

February 8, 2013 Posted by | Psychology, random stuff, statistics, studies | 4 Comments

Promoting the unknown, a continuing series

The first one got a few hundred thousand views so some people might argue that it does not belong in a post like this. On the other hand I’ve heard quite a bit of Rachmaninoff over the years – I’ve even played a bit of his stuff – without ever having come across this piece before, so I’m sure some of you haven’t heard it before either:

I’ve put the rest below the fold…

Continue reading

February 8, 2013 Posted by | music | Leave a comment

Back to work…

I’ve not had lectures for the last two weeks, but tomorrow the new semester starts.

Like last semester I’ll try to ‘work-blog’ some stuff along the way – hopefully I’ll do it more often than I did, but it’s hard to say if that’s realistic at this point.

I bought the only book I’m required to acquire this semester earlier today:

Wooldridge

…and having had a brief look at it I’m already starting to wonder if it was even a good idea to take that course. I’ve been told it’s a very useful course, but I have a nagging suspicion that it may also be quite hard. Here are some of the reasons (click to view in a higher resolution):

DSCN3437

DSCN3439

DSCN3440

I don’t think it’s particularly likely that I’ll cover stuff from that particular course in work-blogs, for perhaps obvious reasons. One problem is the math, wordpress doesn’t handle math very well. Another problem is that most readers would be unlikely to benefit much from such posts unless I were to spend a lot more time on them than I’d like to do. But it’s not my only course this semester. We’ll see how it goes.

February 4, 2013 Posted by | econometrics, economics, statistics | Leave a comment

Stuff

i. PLOS ONE: Till Death (Or an Intruder) Do Us Part: Intrasexual-Competition in a Monogamous Primate.

“Polygynous animals are often highly dimorphic, and show large sex-differences in the degree of intra-sexual competition and aggression, which is associated with biased operational sex ratios (OSR). For socially monogamous, sexually monomorphic species, this relationship is less clear. Among mammals, pair-living has sometimes been assumed to imply equal OSR and low frequency, low intensity intra-sexual competition; even when high rates of intra-sexual competition and selection, in both sexes, have been theoretically predicted and described for various taxa. Owl monkeys are one of a few socially monogamous primates. Using long-term demographic and morphological data from 18 groups, we show that male and female owl monkeys experience intense intra-sexual competition and aggression from solitary floaters. Pair-mates are regularly replaced by intruding floaters (27 female and 23 male replacements in 149 group-years), with negative effects on the reproductive success of both partners. Individuals with only one partner during their life produced 25% more offspring per decade of tenure than those with two or more partners. The termination of the pair-bond is initiated by the floater, and sometimes has fatal consequences for the expelled adult. The existence of floaters and the sporadic, but intense aggression between them and residents suggest that it can be misleading to assume an equal OSR in socially monogamous species based solely on group composition. Instead, we suggest that sexual selection models must assume not equal, but flexible, context-specific, OSR in monogamous species.”

You sort of want to extrapolate out of sample (/…out of species?) here, but be careful:

“Our findings differ from those reported for some monogamous birds, where remaining life-time reproductive success (i.e., the expected future gains) of the individual that initiates or tolerates a ‘divorce’ was higher than if it remained with its initial partner. For example, in kittiwakes (Rissa tridactyla) and many other pair-living birds, but also in some human societies, it is sometimes advantageous to ‘divorce’, if partners prove incompatible [25], [27], [35]. In contrast, our data strongly indicate that break-ups were associated with factors extrinsic to the pair, and that partners did not voluntarily leave or “divorce” as it has been reported for birds, gibbons, and (in at least one case) brown titi monkeys (Callicebus brunneus) [25][27], [36], [37]. On the other hand, in some species (oystercatchers, Haematopus ostralegus), the reproductive success of stable pairs is not only higher, but there are also accrued benefits with increased duration of the pair-bond, independent of effects of age or experience [38]. This was not the case for owl monkeys, since the number of offspring produced did not change with increased duration of the pair-bond (Fig. 2).”

ii. Smbc (click to watch in a higher resolution):

2868 societal complexity
Just to remind you that SMBC is still awesome. Here are a couple of related comics from the site.

iii. PNAS: Microstratigraphic evidence of in situ fire in the Acheulean strata of Wonderwerk Cave, Northern Cape province, South Africa:

“The ability to control fire was a crucial turning point in human evolution, but the question when hominins first developed this ability still remains. Here we show that micromorphological and Fourier transform infrared microspectroscopy (mFTIR) analyses of intact sediments at the site of Wonderwerk Cave, Northern Cape province, South Africa, provide unambiguous evidence—in the form of burned bone and ashed plant remains—that burning took place in the cave during the early Acheulean occupation, approximately 1.0 Ma. To the best of our knowledge, this is the earliest secure evidence for burning in an archaeological context.”

[Another reminder that SMBC is awesome: Here’s a recent comic which is very handy here – it explains what a Fourier transform is, in case you don’t know… (If you actually want to know there’s always wikipedia…)]

iv. I never covered this here and though some of you may already have read it I thought I might as well link to Ed Yong’s write-up on replication studies in Nature published last year. A few quotes from the article:

“Positive results in psychology can behave like rumours: easy to release but hard to dispel. They dominate most journals, which strive to present new, exciting research. Meanwhile, attempts to replicate those studies, especially when the findings are negative, go unpublished, languishing in personal file drawers or circulating in conversations around the water cooler. “There are some experiments that everyone knows don’t replicate, but this knowledge doesn’t get into the literature,” says Wagenmakers. The publication barrier can be chilling, he adds. “I’ve seen students spending their entire PhD period trying to replicate a phenomenon, failing, and quitting academia because they had nothing to show for their time.

These problems occur throughout the sciences, but psychology has a number of deeply entrenched cultural norms that exacerbate them. It has become common practice, for example, to tweak experimental designs in ways that practically guarantee positive results. And once positive results are published, few researchers replicate the experiment exactly, instead carrying out ‘conceptual replications’ that test similar hypotheses using different methods. This practice, say critics, builds a house of cards on potentially shaky foundations.

These problems have been brought into sharp focus by some high-profile fraud cases, which many believe were able to flourish undetected because of the challenges of replication. Now psychologists are trying to fix their field.”

Good luck with that. I don’t see a fix happening anytime soon. A few numbers:

“In a survey of 4,600 studies from across the sciences, Daniele Fanelli, a social scientist at the University of Edinburgh, UK, found that the proportion of positive results rose by more than 22% between 1990 and 2007 (ref. 3). Psychology and psychiatry, according to other work by Fanelli4, are the worst offenders: they are five times more likely to report a positive result than are the space sciences, which are at the other end of the spectrum […]. The situation is not improving. In 1959, statistician Theodore Sterling found that 97% of the studies in four major psychology journals had reported statistically significant positive results5. When he repeated the analysis in 1995, nothing had changed6.”

But maybe other fields are just as bad? Well, as already mentioned the space sciences do better – and that goes for other fields too (though I’d say there seems to be major problems in many areas besides psychology and psychiatry):

replication_graph

A major problem here is that unless you’re actually a researcher in the field or know whom to ask, the file drawer effect can be completely invisible to you.

v. Globalization of Diabetes – The role of diet, lifestyle, and genes. A new publication in Diabetes Care. As usual when they say ‘diabetes’ they mean ‘type 2 diabetes’. Some numbers from the article:

“According to the International Diabetes Federation (1), diabetes affects at least 285 million people worldwide, and that number is expected to reach 438 million by the year 2030, with two-thirds of all diabetes cases occurring in low- to middle-income countries. The number of adults with impaired glucose tolerance will rise from 344 million in 2010 to an estimated 472 million by 2030.
Globally, it was estimated that diabetes accounted for 12% of health expenditures in 2010, or at least $376 billion—a figure expected to hit $490 billion in 2030 (2). […] Asia accounts for 60% of the world’s diabetic population. [Do note that this does not mean that Asian countries are on average overrepresented in the diabetes statistics. Asia also has roughly 60% of the World’s population. – US] […] In 1980, less than 1% of Chinese adults had the disease. By 2008, the prevalence had reached nearly 10% […] in urban areas of south India, the prevalence of diabetes has reached nearly 20% […] Compared with Western populations, Asians develop diabetes at younger ages, at lower degrees of obesity, and at much higher rates given the same amount of weight gain […]

If current worldwide trends continue, the number of overweight people (BMI >25 kg/m^2) is projected to increase from 1.3 billion in 2005 to nearly 2.0 billion by 2030 (6). […] the prevalence of overweight and obesity in Chinese adults increased from 20% in 1992 to 29.9% in 2002 (8) […]

In the NHS (26), each 2-h/day increment of time spent watching television (TV) was associated with a 14% increase in diabetes risk. […] Each 1-h/day increment of brisk walking was associated with a 34% reduction in risk […] Cigarette smoking is an independent risk factor for type 2 diabetes. A meta-analysis found that current smokers had a 45% increased risk of developing diabetes compared with nonsmokers (29). Moreover, there was a dose-response relationship between the number of cigarettes smoked and diabetes risk. [That one I did not know about!] […] Light-to-moderate alcohol consumption is associated with reduced risk of diabetes. A meta-analysis of 370,000 individuals with 12 years of follow-up showed a U-shaped relationship, with a 30–40% reduced risk of the disease among those consuming 1–2 drinks/day compared with heavy drinkers or abstainers (37). […]

common variants of the TCF7L2 gene that are significantly associated with diabetes risk are present in 20–30% of Caucasian populations but only 3–5% of Asians […] Conversely, a variant in the KCNQ1 gene associated with a 20–30% increased risk of diabetes in several Asian populations (43,44) is common in East Asians, but rare in Caucasians […]

Several randomized clinical trials have demonstrated that diabetes is preventable. One of the first diabetes prevention trials was conducted in Daqing, China (58). After 6 years of active intervention, risk was reduced by 31, 46, and 42% in the diet-only, exercise-only, and diet-plus-exercise groups, respectively, compared with the control group. In a subsequent 14-year follow-up study, the intervention groups were combined and compared with control subjects to assess how long the benefits of lifestyle change can extend beyond the period of active intervention (59). Compared with control subjects, individuals in the combined lifestyle intervention group had a 51% lower risk of diabetes during the active intervention period, and a 43% lower risk over a 20-year follow-up.”

vi. Why chess sucks.

vii. If you think your life sucks

February 3, 2013 Posted by | archaeology, biology, data, diabetes, genetics, papers, Psychology, random stuff | 2 Comments

Quotes

i. “To want to meet an author because you like his books is as ridiculous as wanting to meet the goose because you like paté de foie gras.” (Arthur Koestler. This may also apply to bloggers and blogs…)

ii. “Ideals may tell us something important about what we would like to be. But compromises tell us who we are.” (Avishai Margalit)

iii. “If being married was roughly what one thought it would be like, every couple would stay married until death parted them.” (Michelle Mirsky)

iv. “When information is cheap, attention becomes expensive.” (James Gleick)

v. “The point of seeing both sides isn’t to hover between them but to be able to come down on the right side with the right degree of conviction.” (Julian Baggini)

vi. “We praise or find fault, depending on which of the two provides more opportunity for our powers of judgement to shine.” (Nietzsche – ‘Man lobt oder tadelt, je nachdem das Eine oder das Andere mehr Gelegenheit giebt, unsere Urtheilskraft leuchten zu lassen’)

vii. “There is not enough love and kindness in the world to permit us to give any of it away to imaginary beings.” (Nietzsche)

viii. “Life is not what one lived, but what one remembers and how one remembers it in order to recount it.” (Gabriel García Márquez)

ix. “No man thinks there is much ado about nothing when the ado is about himself.” (Anthony Trollope)

x. “Love is like any other luxury. You have no right to it unless you can afford it.” (-ll-)

xi. “There is nothing perhaps so generally consoling to a man as a well-established grievance; a feeling of having been injured, on which his mind can brood from hour to hour, allowing him to plead his own cause in his own court, within his own heart, — and always to plead it successfully.” (-ll-)

xii. “Above all things, never think that you’re not good enough yourself. A man should never think that. My belief is that in life people will take you very much at your own reckoning.” (-ll-)

xiii. “He had married, let us say for love; — probably very much by chance.” (-ll-)

xiv. “Habit is habit, and not to be flung out of the window by any man, but coaxed downstairs one step at a time.” (Mark Twain)

xv. “Nothing so needs reforming as other people’s habits.” (-ll-)

xvi. “All say, “How hard it is that we have to die” — a strange complaint to come from the mouths of people who have had to live.” (-ll-)

xvii. “Few things are harder to put up with than the annoyance of a good example.” (-ll-)

xviii. “His reply had that clarity, objectivity and reasonableness which is possible only to advisers who have completely missed the point.” (Robertson Davies)

xix. “To be apt in quotation is a splendid and dangerous gift. Splendid, because it ornaments a man’s speech with other men’s jewels; dangerous, for the same reason.” (-ll-)

xx. “I am constantly astonished by the people, otherwise intelligent, who think that anything so complex and delicate as a marriage can be left to take care of itself. One sees them fussing about all sorts of lesser concerns, apparently unaware that side by side with them — often in the same bed — a human creature is perishing from lack of affection, of emotional malnutrition.” (-ll-)

February 1, 2013 Posted by | quotes | 2 Comments