Skill and Context Variation in Parental Hiring Probabilities: A Correspondence Study

Last registered on January 20, 2022


Trial Information

General Information

Skill and Context Variation in Parental Hiring Probabilities: A Correspondence Study
Initial registration date
March 25, 2019

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
March 31, 2019, 11:01 PM EDT

First published corresponds to when the trial was first made public on the Registry after being reviewed.

Last updated
January 20, 2022, 4:52 AM EST

Last updated is the most recent time when changes to the trial's registration were published.



Primary Investigator

University of Bath

Other Primary Investigator(s)

PI Affiliation
University of Bath

Additional Trial Information

On going
Start date
End date
Secondary IDs
ERC 680958
Prior work
This trial does not extend or rely on any prior RCTs.
This is a harmonized correspondence study on employer hiring in Finland and the UK, to compare gender differences with parental status the treatment effect. The over-arching research question has two dimensions. First, this study evaluates whether there are gender differences in relative positive callback rates for parents versus childless married individuals at an early stage of the hiring process, and if they differ across low-, medium- and high-skill occupations. Second, it uses a comparative design to generalize results across two diverse country contexts in terms of institutional support gender employment equality and maternal employment in particular. We select the same three gender-neutral occupations for analysis in each labor market, harmonizing education and work experience in each across the countries.
External Link(s)

Registration Citation

Cooke, Lynn Prince and Soyoung Kweon. 2022. "Skill and Context Variation in Parental Hiring Probabilities: A Correspondence Study." AEA RCT Registry. January 20.
Former Citation
Cooke, Lynn Prince and Soyoung Kweon. 2022. "Skill and Context Variation in Parental Hiring Probabilities: A Correspondence Study." AEA RCT Registry. January 20.
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Experimental Details


Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
The outcome of interest is whether there are group differences in relative positive callback rates versus rejections, and if these differ across countries. A positive callback is a request for interview. Given that few employers formally reject unsuccessful applicants, a non-response for the duration of the study will be coded a rejection. We analyze group and country differences in requests to interview versus rejection to ascertain whether we can reject the null hypothesis that employers do not discriminate in favor of fathers or against mothers as compared with their childless peers during initial screening of the hiring process.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
This is a comparative correspondence study assessing potential gender differences in hiring discrimination around parenthood in a low-, medium- and high-skilled occupation in three countries. For the comparative element of this study, the countries were selected given their variation in institutional supports for both class and gender equality. Finland has more extensive labor market institutions and policy support for dual-earning and caring. The German welfare state and tripartite labor market coordination historically supported men's role as family breadwinners. The more liberal UK welfare regime minimizes state intervention in market mechanism affecting either class or gender equality. To compare effects across skill levels, three occupations requiring different levels of education were selected that are also less gender-segregated in all three countries: call center workers, restaurant managers, and accountants.

Two sets of comparable application materials in terms of employment trajectories and accomplishments were developed for each occupation in each country based on national statistics, data bases, LinkedIn profiles, and discussions with country HR experts and recruiting professionals. The sets of application materials were harmonized to equalize number of years of post-secondary education plus work experience within occupations across countries.

External validity of instruments for each occupation has been confirmed via interviews with HR experts, whereas commensurability of sets of application materials (internal validity) has been validated with in-person student and online abs in each country with a total of 884 students.

In fielding, job advertisements will be drawn from online employment databases in each country to provide widest coverage of available jobs. We use a 2x2 within-subject design for effects of parenthood (i.e., for each job ad, two applications will be sent of the same gender, both of whom are married but one is randomly assigned to be a parent (treatment) and the other childless (control)). Parenthood is signaled in the personal information on the resume (doing so is still more normative in Europe). Differences in positive callback rates between men and women are investigated by means of between-subject variation. Gender is manipulated by applicant names, drawn from the most common first names in each country. To evaluate treatment effects, the study documents positive callbacks from employers, comparing group differences in requests for an interview with rejections or non-response.
Experimental Design Details
This is a comparative correspondence study assessing potential gender differences in hiring discrimination around parenthood in a low-, medium- and high-skilled occupation in three countries. Two sets of comparable application materials were developed for each occupation in each country based on national statistics, data bases, LinkedIn profiles, and discussions with country HR experts and recruiting professionals.

We use a 2x2 within-subject design for effects of parenthood. Two either female or two male sets of application materials will be sent in reply to employer job advertisements. All applicants are married; the treatment of interest is parental status. Parental status is randomly assigned and indicates that the applicant has one approximately 2-year-old child. In Finland and Germany, information on family status, along with the age of the child are frequently included among the personal information; we follow suit and signal parenthood and the age of the child by including it with contact information. It is less common to do this in the UK, but HR managers confirmed including family status in the personal information is still done occasionally. We signal the UK child's *age* on the resume under personal interests indicating a hobby with a toddler.

Differences in callback rates between men and women are investigated by means of between-subject variation. Gender is manipulated through applicants’ names, which are clearly identifiable as male or female and selected from each country’s most common first names. In Finland and Germany, it is also usual to include a photo on the resume. Stock professional photos were purchased that approximated the age and expected professional attire of applicants for each occupation.

The definition of skill level follows the International Standard Classification of Occupations (ISCO), and is commensurate across the country-specific occupational classification schemes. High-skilled occupations usually require a tertiary qualification of 3 to 6 years, and include complex problem solving based on specialized knowledge; medium-skilled occupations involve complex technical and practical tasks and often require a post-secondary degree of 1 to 3 years; low-skilled occupations require only the first or possibly second stage of secondary education.

The final selected occupations were accountants (high skill), restaurant managers (medium skill), and call center workers (low skill), based on sex composition, size of occupation, and nature of tasks across organizations. The design aimed for gender balance in each occupation in each country, to avoid conflating discrimination based on parenthood with that based on gender. We first attempted to limit the percentage of women in each occupation to 40 to 60%. This proved too constraining given the high degree of gender segregation in Finland and Germany. Consequently, it was necessary to relax the percentage to less than 70% for Finnish and German accountants.

The second criterion was that a substantial share of the workforce needed to be employed in the selected occupation. Larger occupations ensure that the number of vacancies is high and that each employer can be utilized only once to minimize the imposition on them. Third, the tasks in the selected occupations should not vary substantially across organizations or sectors. This ensures that the developed application materials would be suitable for the majority of job advertisements and more generalizable.

For internal validity, characteristics of applicants in each occupation which affect their hiring probability such as age, education and work experience must be kept constant. External validity requires that the applicants be as typical as possible for their occupation and life stage. Achieving internal and external validity in a cross-nationally comparative correspondence study assessing occupations with different skill levels raises particular challenges. For one, although educational requirements for each occupation are fairly comparable across countries by design, national differences in educational systems result in cross-country variation in the age at which applicants in the same occupation might enter as well as graduate from the educational system.

Another consideration is that the length of parents' employment histories is contingent on the age at which they likely entered parenthood, which varies with education. The cross-occupational average age at first birth ranges from almost 28 to almost 33 years among women, with highly-educated women in all countries becoming parents later than medium- and low-skilled ones.

To balance these aspects, we first harmonize according to mothers’ age at first birth in each country for each occupation, enhancing external validity that might affect employers’ perceptions. Second, to aid cross-country comparisons of occupations, we harmonized what we refer to as “total human capital” for each occupation across countries. We define total human capital as the sum of years in post-compulsory schooling plus work experience. Thus, while the length of education, or years of labor market experience in an occupation might differ slightly across countries, the two added together are harmonized for each occupation. Accountants thus have 12 years of post-secondary schooling and experience; restaurant managers 11, and call center workers 10.

A consequence of this two-step harmonization is that the age of applicants within the same occupation differs slightly across countries (~1 year). We justify the decision to harmonize education and experience rather than age because human capital is more salient to potential employers for young adults than age. HR managers and other recruiting experts confirmed the importance of commensurate education and experience over average age. Thus, any country-variation in positive callback rates for a given skill level likely stems from institutional effects rather than the (minor) cross-country variation in ages for each occupation.

Childless women and mothers of the same age may not have comparable years of work experience, however, as mothers tend to interrupt employment as a result of a birth. This raises the possibility that employers may discriminate against mothers not because of their status, but because they may have less experience at a given age than their childless peers. However, determining a plausible career-related interruption for the fictitious applicants is problematic. Not only do the selected countries differ in the length of parental leave, the duration of family-related employment interruptions varies substantially among women within a country. Furthermore, discussions with HR experts highlighted that parental leave that occurs during an ongoing employment episode is seldom itemized on the resume. For this reason, we follow existing studies and keep work experience between childless applicants and parents constant. Additionally, the employment trajectories on each occupational resume were made to be commensurate in career progression and accomplishments. The number of job moves is held constant, as is the size of the firms. Commensurate accomplishments further minimize the importance of deduced employment interruptions.

A final issue is that Finnish men are affected by mandatory conscription of six months to one year after secondary schooling. Consequently, a gap year was added to all Finnish medium- and high-skilled applicants between secondary and tertiary education. This gap accounts for men’s conscription, but works equally well for women, as it is common for all Finnish students to take a gap year before entry into higher education. Low-skilled men, in turn, are assigned six months of military service. Lower-skilled Finnish women are given six months in a job unrelated to call centers.

The commensurability of the application materials was validated via a series of lab experiments in the three countries. Students rated each of two application packets using a questionnaire containing 28 job-related attributes. They were also asked whether they would hire both candidates, and which one if they could only hire one. Initial materials that were not commensurate were revised and re-validated in subsequent lab and online studies. Commensurability of photos along 10 job-related attributes was also tested. (Total N=884)

Custom software has been developed to scrape for suitable job ads from two online sites in each country, and randomly compile the appropriate application packet. The selected template of resume and cover letter (and for Germany, reference letter), order of applications, and names of applicants are assigned randomly, whereas photos are assigned randomly to the Finnish and German resumes. If the posted job advertisement is more than 50 kilometers from the applicant’s listed home address, the software inserts an additional sentence in the cover letter, that the applicant is looking to move to the region to be closer to family.

The start of fielding will be staggered, beginning in mid-April in the UK, end of April in Finland, and mid-May in Germany. In each country, the first two months of fielding constitute a piloting phase to refine the types of jobs replied to and confirm that employers view the application sets as commensurate. For the pilot phase, the software will randomly select from among the jobs, so that we can do any instrument refinements without eliminating a large number of potential employers (as each employer is only used once). Top-level information is gathered relating to size of employer, sector, industry, nature of job (part-time), region, desirable special skills, and distance from applicant. The experimental data of interest are invitations to interview relative to rejections.
Randomization Method
All randomization of application materials is done via a computer software program.
Randomization Unit
Which gender pair to send randomized for responding to suitable job advertisement. Individual randomization in terms of treatment, template, order sent, and for Finland and Germany, the CV photo.
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
Not applicable.
Sample size: planned number of observations
Responding to 500 job advertisements per occupation in each country (1000 applications sent x 3 occupations x 3 countries)=9000 applications
Sample size (or number of clusters) by treatment arms
A pair of same-gender applications is sent to each of 500 job advertisements for each occupation, one being the control and the other the treatment. So of the 3000 total applications to be sent in each country, 1,500 are the treatment, and 1,500 the control. Within each country, 750 women and 750 men are in the treatment group (parent), whereas 750 men and 750 women are in the control (childless). This gives 250 women and 250 men in the treatment group in each occupation; and 250 women and 250 men in the control group in each occupation.
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
The goal is to have a sufficient sample size of job ads in each occupation to yield beta=.1 (power .9) and alpha=.05 for population gender differences between affirmative call-backs for the treatment (parents) versus controls (childless) across occupations and countries. Note in existing correspondence studies this is often relaxed to beta=.2 (power .8) and alpha=.20. However, studies testing parental discrimination have not published their power calculations. As relative callback rates for parents relative to non-parents of each gender differ substantially across occupations and countries, it is difficult to do power calculations to estimate necessary sample size before piloting. The initial plan is therefore to reply to 500 job ads (1000 applications sent) for each occupation in each country as noted above. Funding is available to keep fielding into 2021 if necessary.

Institutional Review Boards (IRBs)

IRB Name
European Research Council Ethics Committee
IRB Approval Date
IRB Approval Number
ERCEA/BT/ ercea.b.1(2016)3148812
IRB Name
University of Turku Ethics Committee
IRB Approval Date
IRB Approval Number
Statement 20/2016
IRB Name
Berlin Social Science Center Research Ethics Committee
IRB Approval Date
IRB Approval Number
IRB Name
Department of Social and Policy Sciences Ethics Committee, University of Bath
IRB Approval Date
IRB Approval Number


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