Archive for Science Po’

how a hiring quota failed [or not]

Posted in Books, Statistics, University life with tags , , , , , , , , , , , , , on February 26, 2019 by xi'an

This week, Nature has a “career news” section dedicated to how hiring quotas [may have] failed for French university hiring. And based solely on a technical report by a Science Po’ Paris researcher. The hiring quota means that every hiring committee for a French public university hiring committee must be made of at least 40% members of each gender.  (Plus at least 50% of external members.) Which has been reduced to 30% in some severely imbalanced fields like mathematics. The main conclusion of the report is that the reform has had a negative impact on the hiring imbalance between men and women in French universities, with “the higher the share of women in a committee, the lower women are ranked” (p.2). As head of the hiring board in maths at Dauphine, which officiates as a secretarial committee for assembling all hiring committee, I was interested in the reasons for this perceived impact, as I had not observed it at my [first order remote] level. As a warning the discussion that follows makes little sense without a prior glance at the paper.

“Deschamps estimated that without the reform, 21 men and 12 women would have been hired in the field of mathematics. But with the reform, committees whose membership met the quota hired 30 men and 3 women” Nature

Skipping the non-quantitative and somewhat ideological part of the report, as well as descriptive statistics, I looked mostly at the modelling behind the conclusions, as reported for instance in the above definite statement in Nature. Starting with a collection of assumptions and simplifications. A first dubious such assumption is that fields and even less universities where the more than 40% quota was already existing before (the 2015 reform) could be used as “control groups”, given the huge potential for confounders, especially the huge imbalance in female-to-male ratios in diverse fields. Second, the data only covers hiring histories for three French universities (out of 63 total) over the years 2009-2018 and furthermore merges assistant (Maître de Conférence) and full professors, where hiring is de facto much more involved, with often one candidate being contacted [prior to the official advertising of the position] by the department as an expression of interest (or the reverse). Third, the remark that

“there are no significant differences between the percentage of women who apply and those who are hired” (p.9)

seems to make the all discussion moot… and contradict both the conclusion and the above assertion! Fourth, the candidate’s qualification (or quality) is equated with the h-index, which is highly reductive and, once again, open to considerable biases in terms of seniority degree and of field. Depending on the publication lag and also the percentage of publications in English versus the vernacular in the given field. And the type of publications (from an average of 2.94 in business to 9.96 on physics]. Fifth, the report equates academic connections [that may bias the ranking] with having the supervisor present in the hiring committee [which sounds like a clear conflict of interest] or the candidate applying in the [same] university that delivered his or her PhD. Missing a myriad of other connections that make committee members often prone to impact the ranking by reporting facts from outside the application form.

“…controlling for field fixed effects and connections make the coefficient [of the percentage of women in the committee] statistically insignificant, though the point estimate remains high.” (p.17)

The models used by Pierre Deschamps are multivariate logit and probit regressions, where each jury attaches a utility to each of its candidates, made of a qualification term [for the position] and of a gender bias most surprisingly multiplying candidate gender and jury gender dummies. The qualification term is expressed as a [jury free] linear regression on covariates plus a jury fixed effect. Plus an error distributed as a Gumbel extreme variate that leads to a closed-form likelihood [and this seems to be the only reason for picking this highly skewed distribution]. The probit model is used to model the probability that one candidate has a better utility than another. The main issue with this modelling is the agglomeration of independence assumptions, as (i) candidates and hired ones are not independent, from being evaluated over several positions all at once, with earlier selections and rankings all public, to having to rank themselves all the positions where they are eligible, to possibly being co-authors of other candidates; (ii) jurys are not independent either, as the limited pool of external members, esp. in gender-imbalanced fields, means that the same faculty often ends up in several jurys at once and hence evaluates the same candidates as a result, plus decides on local ranking in connection with earlier rankings; (iii) independence between several jurys of the same university when this university may try to impose a certain if unofficial gender quota, a variate obviously impossible to fill . Plus again a unique modelling across disciplines. A side but not solely technical remark is that among the covariates used to predict ranking or first position for a female candidate, the percentage of female candidates appears, while being exogenous. Again, using a univariate probit to predict the probability that a candidate is ranked first ignores the comparison between a dozen candidates, both male and female, operated by the jury. Overall, I find little reason to give (significant) weight to the indicator that the president is a woman in the logistic regression and even less to believe that a better gender balance in the jurys has led to a worse gender balance in the hirings. From one model to the next the coefficients change from being significant to non-significant and, again, I find the definition of the control group fairly crude and unsatisfactory, if only because jurys move from one session to the next (and there is little reason to believe one field more gender biased than another, with everything else accounted for). And for another my own experience within hiring committees in Dauphine or elsewhere has never been one where the president strongly impacts the decision. If anything, the president is often more neutral (and never ever imoe makes use of the additional vote to break ties!)…

Infomocracy [book review]

Posted in Books, Travel with tags , , , , , , , , , on June 17, 2017 by xi'an

Infomocracy is a novel by Malka Older set in a near future where most of the Earth is operating under a common elective system where each geographical unit of 100,000 people elect a local representative that runs this unit according to the party’s program and contributes to elect a Worldwide government, except for some non-democratic islets like Saudi Arabia. The whole novel revolves around the incoming election, with different parties trying to influence the outcome in their favour, some to the point of instating a dictature. Which does not sound that different from present times!, with the sligth difference that the whole process is controlled by Information, a sort of World Wide Web that seems to operate neutrally above states and parties, although the book does not elaborate on how this could be possible. The story is told through four main (and somewhat charicaturesque) characters, working for or against the elections and crossing paths along the novel. Certainly worth reading if not outstanding. (And definitely not “one of the greatest literary debuts in recent history”!)

The book is more interesting as a dystopia on electoral systems and the way the information revolution can produce a step back in democracy, with the systematisation of fake news and voters’ manipulation, where the marketing research group YouGov has become a party, than as a science-fiction (or politics-fiction) book. Indeed, it tries too hard to replicate The cyberpunk reference, William Gibson’s Neuromancer, with the same construct of interlacing threads, the same fascination for Japan, airports, luxury hotels, if not for brands, and a similar ninja-geek pair of characters. And with very little invention about the technology of the 21st Century.  (And a missed opportunity to exploit artificial intelligence themes and the prediction of outcomes when Information builds a fake vote database but does not seem to mind about Benford’s Law.) The acknowledgement section somewhat explains this imbalance, in that the author worked many years in humanitarian organisations and is currently completing a thesis at Science Po’ (Paris).

major confUSion

Posted in Books, pictures, Statistics with tags , , , , , , , , on November 19, 2016 by xi'an

crossing the Seine in RER C near Maison de la Radio, Nov. 09, 2012In a recent evening talk-show on France Inter, the French national public radio, the debate was about the [bad] surprise election of the donald and the fact that the media had missed the result, (self-)blaming a disconnection with the “real” country. One of the discussants, Julia Cagé, Professor of Economics at Science Po’, started the discussion with the amazing confusion [at 5’55”] between the probability that Hillary Clinton would win [evaluated at 84% on the last day] and the percentage of votes in her favour [which was around that figure in Manhattan]…

On a related if minor theme, my post on Flaxman et al.’s early [if preliminary] analysis of the said election got so many views that it became the most popular post for 2016! (If not competing with Ross Ihaka’s call to simply start over with R!)

And yet another related entry today in Libération, blaming the disastrous result partly on the social media and their algorithms (again!) that favour items of information (or dis-information) from the same perspective and do not rank those items by their reliability… The author of the tribune is an econometrician at Essec, but there is no methodological content in this ideological entry that seems to call for a super-monitor which would impose (how?) diversity and (which?) ranking on social media. A post-truth era, for sure! Shifting the blame from the deplorable voters themselves to anything else…