Causal Inference: The Mixtape

Here’s a nice overview of causal inference by Scott Cunningham. Yes, you get an entire book as a free download, and it’s got you covered from probability to Pearl’s directed acyclical graphs, from instrumental variables to synthetic control. It comes across quite friendly, but has enough econometrics to scare many off. I quite enjoyed the historical bits thrown in here and there to explain where the methods came from.

http://scunning.com/mixtape.html

Taxing immigrants is likely to deter them: some data

In Switzerland, there’s currently a discussion on taxing immigrants (well make them pay a fee, not really a tax: “Zuwandererabgabe”) as a means to reduce regulate immigration. The intuition is straightforward: immigrants cause costs to the country of destination (infrastructure, environment), and we can recover at least some of the expenses from them. Reiner Eichenberger suggests to tax immigrants (refugees excluded) between CHF 12 and 15 every day (he likens this to a visitor’s tax tourists pay) for the first 3 to 5 years — that’s around CHF 5000 a year. This does not affect the freedom to move, but introduces costs which he argues would reduce immigration.

George Sheldon highlights that such an immigrant tax would most likely be covered by employers, not the immigrants. Immigrant workers can choose between many countries (of destination), while the employers need a worker in a particular location: this gives the immigrant worker more power in negotiating who covers a potential immigrant tax. An immigrant tax is also an opportunity cost, so immigrants are likely to stay longer — which actually increases the share of immigrants in Switzerland.

Data

In this debate, alternative payments are also discussed, such as deposits. What lacks, however, is any empirical data on how immigrants are likely to react. Well, here I present data from a non-representative survey I conducted in April 2011 — when this idea of taxing immigrants was discussed last time (I wrote some of the text below in 2011, too) . The survey covers university students in Germany (Osnabrück) and Albania (Tirana), and asks about plans to emigrate. It also asks whether the prospect of paying a deposit or a non-refundable fee would deter them. Let’s be clear that these are survey questions, so we can only capture what they say, not actual behaviour; and university students may be a particular group. There are 122 responses from German students, and 41 from Albanian students in the data, studying many different degrees.

The intuition behind the case selection was to capture two different immigrant population — taking the perspective of Switzerland. On the one hand, there are the typically highly-skilled immigrants from Western Europe. They constitute a group of immigrants often considered benevolently, although not unreservedly so. On the other hand, Albanians are often regarded with suspicion in Switzerland, regardless of their qualification. Cultural differences tend to be highlighted in popular discourse. The expectation is that both in Germany and Albania, university graduates are a population of potential emigrants, although it would be wrong to expect everyone considering emigration.

The survey included a series of question asking respondents what is important in life (family, friends, politics, money, religion), and a number of attitudinal items. These attitudinal items capture whether men should be privileged over women if jobs are scarce, and if the native population should be privileged in the same situation. Further items asked whether immigrants should integrate better, if immigrants should keep their traditions or whether they should adjust to local customs.

Expectations

In the absence of data, what could we expect? On the one hand, from a purely economic perspective, it can be expected that migration fees and deposits are a deterrent to migration. Other things being equal, a rational profit-maximizing individual will choose a different country of destination, where no such migration fee is levied. At the same time, the presence of a migration fee or a deposit could act as an important signal to potential migrants: that they are not welcome, or only welcome under specific circumstances. The migration fee in this case acts as a symbolic rather than economic disincentive. In either case, the expectation is that the presence of migration fees and deposits would influence migration decisions.

In economic terms, there is a difference between a migration fee and a deposit. A migration fee is non-refundable, and can be regarded as an (artificial) opportunity cost. A deposit, in contrast, is refundable under certain circumstances. It can act as insurance against costs to the country of destination — particularly in relation to crime and efforts to extradite unwanted immigrants. Given its potentially refundable nature, economic incentives may differ. The willingness to pay a small deposit is expected to be higher than the willingness to pay a migration fee and a high deposit.

Results

58% of respondents have thought about emigrating after their studies. Of these, however, 63% have no concrete plans, and only 16% have gathered information. 25% have considered moving to Switzerland, 75% have only considered different countries.

In Germany, 61% of respondents have thought about emigrating after their studies, of which 69% have no concrete plans, and 11% have gathered information. 30% have considered Switzerland.

In Albania, 51% of respondents have thought about emigrating after their studies, of which 43% have no concrete plans, and 33% have gathered information. 10% have considered Switzerland.

What’s important to choose a country of destination? 73% mentioned job opportunities, 36% career opportunities, 28% friends, 16% the salary, 36% living costs, and 16% migration costs. For 57% language is an important criterion. 38% think they need a concrete job offer, and for 36% their partner is a deciding factor.

How important are migration costs? None of them thought that costs were irrelevant, but fewer than half (47%) consider these costs central or rather central.

Would an immigration fee affect your choice of country? Let’s look at the percentage of respondents stating that such a fee would affect their choice of country, beginning with refundable deposits:

€1,000: 18% think this affects their choice
€5,000: 43% think this affects their choice
€10,000: 78% think this affects their choice
€20,000: 84% think this affects their choice

So yes, migration fees seem to affect the choice of country, but only the larger amounts can deter the majority — and for 16% paying €20k is not enough to change their minds…

How about non-refundable fees?

€1,000, non-refundable: 42% think this affects their choice
€5,000, non-refundable: 73% think this affects their choice
€10,000, non-refundable: 89% think this affects their choice
€20,000, non-refundable: 94% think this affects their choice

Unsurprisingly, non-refundable fees have a stronger ‘effect’, with lower amounts already having a significant impact. Given the general opportunity costs of moving to another country, the many respondents deterred by an additional €1,000 suggests that the symbolic component of such migration fees can be substantial — and migration fees are not only part of an economic cost-benefits analysis.

There appear to be no gender differences in the willingness to pay a migration fee, and differences in stated job prospects are not associated with differences in the willingness to pay a migration fee. Young individuals, however, seem more willing (or less reluctant) to pay. For this, I have simply added the responses to the different questions on migration fees (thus a higher value means more of the questions were answered with having an impact on country choice = more reluctance to pay). The correlation between age and the sum of the fee questions is 0.25 (p=0.016). Young individuals are generally more risk-taking, so this is not a surprise.

You can download the data from my Dataverse.

Should I pay my interview respondents?

As an interdisciplinary institute, we have recently discussed whether (and under what circumstances) we should pay interview respondents and participants in our studies? Here are a few things I have compiled for this purpose. At this point, I really would like to thank the participants of the Rencontre Scientifique SFM on 28 June 2016 for the discussion and comments.

General Ethical Principles
General ethical principles apply, and the following table reviews a list of general ethical principles taken from the SFM Ethics Guidelines in view of the question of paying interview respondents. The focus is on interview participants in a wider sense to include focus groups, expert interviews, laypersons with expert knowledge, and informants.

Principle Impact of Payment Evaluation
no harm to subjects and researcher not affected by payment neutral
potential benefits to subjects payment clearly as a benefit to subjects positive
informed consent should normally be obtained: participants should be aware of nature of research and their involvement; participants have a right to withdraw consent at any time without giving any reason payment creates incentives to participate when there is no consent; so payment needs to be separated from completion negative
accordance to relevant law and legislation payment is legal, but may be taxable neutral
researchers must respect the rights, dignity, and interests of participants, including assurances of confidentiality and anonymity payment does not affect these obligations on part of the researcher neutral
research involving children should obtain consent from both the parents and the children, consistent with their capacity payment does not affect this neutral
reduce likelihood that research experience is disturbing to participants and others payment does not change this, but may compensate for inadvertent violation of this principle positive
avoid actions that may have deleterious consequences for researchers who come after or undermine reputation of the discipline payment may increase the expectation that other researchers pay (which can undermine future researchers to carry out the same kind of research), payment as such is unlikely to undermine the reputation of the discipline, but may enhance it mixed
ensure that funders appreciate the ethical obligations of researchers not affected, if there is an ethical obligation to pay, this needs to be communicated to the funder – the fact that the project will be more expensive than a competitor’s is no excuse not to follow research ethics neutral

Disciplinary Traditions in Experiments
In experiments, economists almost always pay their participants. Economists worry that without payment there is no real incentive to follow the instructions. With payment there is a possible problem with satisficing.

In psychology, they hardly ever do. Psychologists worry that with payment inherent preferences and motivations are overruled. Without payment there is a potential problem with participants trying to please the researchers.

General Considerations

Participants and their contributions should be respected.

Observation Impact of Payment Evaluation
Respondents in professional capacity are already paid unclear payment not necessary
Respondents in professional capacity may be ordered to participate unclear unclear
People like to talk (about themselves) unnecessary commodification payment not necessary
No obligation to participate, but payments can be interpreted as coercion1 (Boddy et al. 2010), people from poorer background may be more susceptible to this kind of influence undermines informed consent, especially for some parts of society negative
Payment can reduce non-response bias, precisely because payment incites participation (Boddy et al. 2010; Grady 2011). increases participation rates, reduce non-response bias positive
Payment often facilitates recruitment (Grady 2011) facilitates recruitment positive
Is the influence is undue: likely to distort judgement of risks and benefits? Likely to affect giving consent? Payment should never trump freely given informed consent.2 may affect judgement of individuals negative
Reimbursing expenses is different from paying for time, skills, and expertise. The latter are subject to employment law, thus taxable income.3 depends on the form of payment mixed
Payment may lead to fictional accounts4 5 invalid responses negative
Paying creates an obligation that can blur boundaries and undermine trust. undermining trust negative
May skew samples (Grady 2011) skew samples negative
Not paying may introduce bias by excluding participants, e.g. poor who cannot afford to participate, despite having something important to say (Thompson 1996) reduce coverage bias positive

Boddy et al. (2010) suggest: (1) create guidelines when and how payments are made, (2) payment is justified, (3) ensure that those who withdraw are still paid, (4) carefully consider cases where consent may be given only because of the payment

Specific Considerations

In the social sciences it is uncommon to pay interview participants. This, however, does not constitute an ethic statement. Direct costs incurred by participants (e.g. travel expenses) should always be reimbursed.

Sometimes it is necessary to pay to ensure participation (e.g. interviews with prostitutes or taxi drivers (e.g. Gambetta and Hamill 2005), some online survey panels). A similar case is paying for survey respondents, where payment may be necessary to get access.

There are some ideal-typical cases of participants, but in reality the boundaries are fluid: (1) Focus groups, (2) experts in their professional capacity, (3) lay persons with expert knowledge, and (4) informants.

(1) Focus Groups

Participants in focus groups are normally paid. Participants are generally paid a flat amount (depending on the circumstances) to cover travel and a symbolic amount. Focus group participants need to prepare for the focus group, they are asked to come to the venue the researchers specify at a given time (in the other cases considered here, it is the researcher who travels and adjust his or her schedule). The participants are asked to follow the design and have less scope to deviate from it. Payment also creates an informal obligation to turn up, and often motivates participants who would otherwise not participate in such an endeavour despite supporting the research project otherwise: the specificities of a focus group (time, scheduling, and preparations) make it relatively costly to the participants.

(2) Experts in their Professional Capacity

Experts in their professional capacity are not normally paid. There is no reason to. Experts in their professional capacity are in a way paid to participate, but potential direct expenditures (e.g. travel) should be reimbursed if their employer does not cover them. Experts are free to tell the researchers what they want and have more scope to deviate from the questionnaire and participants in a focus group.

(3) Lay Persons with Expert Knowledge

Lay persons with expert knowledge are not normally paid. Lay persons with expert knowledge are like experts in that they are consulted as witnesses and for providing a synthesis – describing the situation of a group, for instance, not (just) about the person in question. They may be active in associations, often on a voluntary basis. At the same time, given their position and expert knowledge, they are often frequently consulted by researchers. They are free, however, to decline participation in a way experts in their professional capacity may not be. They often agree to participate because they have a message to share, and their contribution should be sufficiently recognized. Like with other participants, direct costs (e.g. travel) should always be reimbursed. Lay persons with expert knowledge are free to tell the researchers what they want and have more scope to deviate from the questionnaire and participants in a focus group.

(4) Informants

Informants are not normally paid. Informants are free to decline participation. However, informants can be in a precarious situation (e.g. undocumented migrants). Researchers frequently provide symbolic gestures like vouchers in these situations, but in order not to create pressure to participate, these gestures should probably not be mentioned during recruitment: informants should not participate only or largely because of the rewards. Informants are free to tell the researchers what they want and have more scope to deviate from the questionnaire than participants in a focus group, and contrary to experts and lay persons with expert knowledge, no synthesis is expected on part of the informant.

Should sensitive topics mean more payment? – There is no reason why this should be the case, if anything larger payments can lead to distorted answers.

Should those with higher income receive more payment? – No, payments are allowances and not payments to cover (potential) loss of earnings. The situation is different where access to a group of informants is contingent on payment (e.g. prostitutes).

Conclusion

The decision whether to pay has to be determined on a case-by-case basis

We now recommend that researchers consult the specific consideration above when considering whether to pay participants or not.

1 payment is not coercion (no harm threatened), but may be undue inducement/influence (an offer one cannot refuse, controlling or irresistible influence, strong enough to compel participation against interest) (Grady 2011)

2 money may affect risk assessments and consent (Grady 2011)

3 Free prize draws are frequently used in marketing (not subject to employment laws, not subject to lottery laws). The nature of prizes, cash equivalents, and notification of winners must be clear (Boddy et al. 2010).

4 Film-makers do not pay participants, it’s regarded a “privilege” to tell one’s story, although travel expenses are generally reimbursed; usually there is no money in documentaries; they worry that if you pay, people will tell you what they think you want to hear; experts should be credited; most experts are happy to contribute; when filming with really poor populations, the crew often make a gesture after filming, e.g. food, clothes. Film-makers are worried that paying in advance (or agreeing to pay) leads to fictional accounts.

5 Journalists typically don’t pay. They worry that it affects what people say.

References
Boddy, J., T. Neumann, S. Jennings, V. Morrow, P. Alderson, R. Rees, and W. Gibson. 2010. The Research Ethics Guidebook: A Resource for Social Scientists. http://www.ethicsguidebook.ac.uk/.

Gambetta, D., and H. Hamill. 2005. Streetwise: How Taxi Drivers Establish Their Customers’ Trustworthiness. New York: Russel Sage Foundation.

Grady, Christine. 2011. “Ethical and Practical Considerations of Paying Research Participants.” Department of Clinical Bioethics Clinical Center/NIH. https://www.niehs.nih.gov/research/resources/assets/docs/ethical_and_practical_considerations_of_paying_research_participants_508.pdf.

Ruedin, Didier. 2016. “Ethics Guidelines SFM.” SFM University of Neuchâtel.

Thompson, Sonia. 1996. “Paying Respondents and Informants.” Social Research Update 14: 1–5.

Ethnic discrimination in hiring decisions: a meta-analysis of correspondence tests 1990–2015

Eva Zschirnt and I have undertaken a meta-analysis of correspondence tests in OECD countries between 1990 and 2015. It is now available on the website of JEMS. We cover 738 in 43 separate studies conducted in OECD countries between 1990 and 2015. In addition to summarizing research findings, we focus on groups of specific tests to ascertain the robustness of findings, emphasizing (lack of) differences across countries, gender, and economic contexts. Discrimination of ethnic minority and immigrant candidates remains commonplace across time and contexts.

C4P: highly-skilled migrants and brain waste in the (European) labour market; IMISCOE 2016 in Prague

taxidriverWe are seeking paper presentations on highly-skilled migrants and brain waste in the (European) labour market for the annual IMISCOE conference in Prague, 30 June – 2 July 2016. See full call for further information; submit abstracts on-line by 17 January 2016.

We are seeking innovative quantitative papers that examine the (different) reasons and consequences of brain waste, including contributions to better measurement of skills mismatch. Possible research questions are the propensity of immigrants to become self-employed as a result of over-education, their propensity to (re-) migrate due to over-education, or their likelihood to send remittances. We particularly welcome papers that fully account for the gender dimension of brain waste.

Furthermore, the current literature does not adequately address the question of the skills mismatch a migrant would have experienced – if any – if he or she stayed in the country of origin. Notions of brain drain, and brain waste should ideally take into consideration these counterfactuals. After all, the migrant scientist working as a taxi driver may not have found adequate employment in the country of origin.

Image credit