Volume 55     Number 3    Winter 2018      Editor: Tara Behrend

Meredith Turner
/ Categories: 553

Revisiting the 2016 SIOP Income & Employment Survey: Gender Pay Gap

Erin M. Richard, Natalie Wright, Sarah Thomas, Anna Wiggins, Amy DuVernet, Brandy Parker, and Kristl Davison

The focus on gender equality in the workplace—particularly around gender and pay—continues to

 be a topic of interest in popular press (e.g., Veira, 2017) and research (e.g., Leslie, Manchester, & Dahm, 2017). The field of I-O psychology is not exempt from this troubling issue. The SIOP 2016 Income and Employment Report found that although the gender pay gap continues to close, with the income ratio improving from 87.9% in 2012 to 89.7% in 2015, there is still a gender-based difference in pay (Poteet, Parker, Herman, DuVernet, & Conley, 2017). SIOP’s own Institutional Research Committee, which is now responsible for the SIOP Income and Employment Survey, has continued to explore the data from the 2016 survey to better understand the relationship between gender and pay within the I-O community.


Despite notable strides made towards gender equality in the workplace, men and women are still not paid equally. According to data from the United States Census Bureau, women earned, on average, only 80% of what men earned in 2015 (Proctor, Semega, & Kollar, 2016). Although the gap has narrowed since 1960, the rate at which the gap is closing has slowed (American Association of University Women, 2017). This gap is at its widest approximately 15–20 years after individuals enter the workforce and, interestingly, is wider for college graduates than those who did not graduate college. Women who are married and/or have small children are particularly affected (Goldin, Kerr, Olivetti, & Barth, 2017). Given our research and focus on the workplace, we expect our field may not be as susceptible to gender inequality as other fields. Indeed, as reported in our recent salary survey (Poteet et al., 2017), I-O psychologists of different genders enjoy a more comparable salary than individuals in other fields. Still, understanding the extent to which such a gap exists within various career paths in the field of I-O psychology, and the predictors of this gap, is an important first step in improving pay equity in our profession.


Research on the Gender Pay Gap


The process by which the gender pay gap is created may begin as soon as a formal job offer is made. Leibbrandt and List (2015) found that women were less likely than men to negotiate for higher pay when there was no specific mention made of salary being negotiable. However, when there was explicit mention of salary being negotiable, women were just as likely as men to negotiate for higher pay. In a survey of undergraduate students, Hogue, DuBois, and Fox-Cardamone (2010) discovered that women had lower expectations than did men about their entry-level pay and their peak career pay. Interestingly, both men and women who planned on entering female-dominated occupations expected to earn less than did those (of both genders) who planned on entering male-dominated occupations, although this difference was more pronounced for women than for men.


Authority level may also play a role in salary differences. A study of chief procurement officers found that women in this position were paid less than men, had fewer supervisory responsibilities, and controlled fewer resources. The authors argued that these differences could be explained by authority level; women had less authority than men, and lower authority was related to lower pay (Alkadry & Tower, 2011).


There are situations, however, in which women are not paid less than men. Among individuals holding graduate degrees, within-major pay differences are generally nonexistent, possibly because graduate degrees tend to be more closely linked to job opportunities (Morgan, 2008). Particularly in organizations with diversity goals, high-potential women may be seen as important to advancing those goals, and in such situations these women may be paid more than men for comparable positions (Leslie et al., 2017). 


The field of I-O psychology has several characteristics which may serve to minimize the pay gap between men and women. Most I-O psychologists hold graduate degrees, and as noted by Morgan (2008), the pay gap between genders is nearly nonexistent for those holding graduate degrees. Additionally, although psychology as a whole is generally perceived as being a female-dominated field, I-O psychology was until quite recently a male-dominated field, as evidenced by the gender breakdown of salary survey respondents over time (see Poteet et al., 2017). However, other relevant factors, such as women being less likely to negotiate at the outset of a job when there is no explicit invitation (Leibbrandt & List, 2015) and the “motherhood penalty,” whereby women with children are paid less (Lips & Lawson, 2009) may still affect pay equity within I-O psychology.


Survey Background


The 2016 Income and Employment Report provides a detailed investigation of the latest SIOP salary survey data collection effort and results, but readers looking for a high-level overview of the survey (and results) may want to turn to the TIP article published in winter 2017 (DuVernet, Poteet, Parker, Conley, & Herman, 2017). The survey was administered in the summer of 2016, with questions focused on SIOP members’ responses to questions about compensation and work experience from 2014 and 2015. In the current article, we conducted additional analyses to investigate the presence (or lack thereof) of gender differences in pay and work experiences along with potential causes for such differences.


There were 1,120 usable responses from the survey, with female respondents making up 49% of the total responses. We focused on those who indicated they were full-time employees, resulting in 1,069 respondents. (For more details on sample characteristics, see 2016 Income and Employment Report.)


Does SIOP Have a Gender Pay Gap?


Unfortunately, results point to the presence of a gender pay gap within the field of I-O psychology. Both median and mean differences across genders were significant. Male respondents reported earning 11.5% higher median incomes and 17.7% higher mean incomes. Specifically, the mean income for male respondents was $138,873, whereas the mean reported income earned by female respondents was $117,985 (t(1,056) = 4.093, p<.001).


Table 1 below presents descriptive statistics for men’s and women’s incomes in 2015. These results provide further insight into gender income disparities. Consistent with the calculation method employed by the United States Bureau of Labor Statistics, the ratio of women’s median income to men’s median income was used to examine earning equality across genders.  Interestingly, the differences in incomes at the 10th and 25th percentiles are relatively small (favoring women at the 10th percentile). Beginning at the 50th percentile and continuing up, the differences become increasingly larger. Thus, it appears that it is at the mid to upper levels of income where gender income differences become more pronounced. Income increases as I-O psychologists advance in their careers, but the gender pay gap appears to be more pronounced at higher levels of pay.



Table 1

Descriptive Statistics for 2015 Primary Incomes by Gender







Mean income



Median income



Female to male income ratio:





















In What SIOP Subgroups Do We See the Greatest Gender Pay Gap?


To better understand where the differences arise, we parsed the data to examine potential moderators of the gender pay gap. Figure 1 shows gender differences in median salary across different levels of experience. These data are somewhat consistent with research demonstrating that the largest gap in pay between genders occurs 15–20 years postgraduation (Goldin et al., 2017); SIOP members with 15-19 years of experience showed the second largest gender pay gap.  However, the largest gender pay gap in our sample was among those respondents with more than 30 years of I-O-related experience. Salary increases as I-O psychologists advance in their careers, and it seems the gender pay gap becomes more pronounced as this increase occurs.


Figure 1. Impact of Experience on I-O Psychologist Gender Pay Gap


Figure 2 parses the 2015 base salary data by gender and industry.  Within the academic subsample, we break the data up by the two most common department types, psychology and business/management. Within the practitioner subsample, we parsed the data by the four most frequent types of employers.  A few patterns are interesting to note here. First, within those employed in academic settings, there appears to be a much larger gender pay gap in business/management departments compared to psychology departments.  Second, among practitioners, those working for consulting firms reported the largest gap, whereas those working for nonprofits reported the smallest gap.



Figure 2. Impact of Career on I-O Psychologist Gender Pay Gap


Figure 3 compares the ratio of female to male salary across the five locations where we see the highest concentration of SIOP members. Of particular note, female I-O psychologists in Washington, DC reported a higher median salary than male I-O psychologists in that area.



Figure 3. Impact of Location on I-O Psychologist Gender Pay Gap


Can the Gender Pay Gap Be Explained by Other Drivers of Salary?


After examining the pay gap across the different subgroups highlighted above, we sought to investigate the extent to which the SIOP gender pay gap may be explained by other factors known to predict salary —namely, experience, authority, and education. These analyses were limited to individuals who indicated full-time employment, with a focus on variables that were applicable to the entire sample (e.g., PsyD vs PhD would only apply to those with doctorates). Using hierarchical regression analysis (see Table 2), we first estimated the extent to which years of I-O-related work experience, number of employees managed or supervised, and I-O degree (master’s vs. PhD) predicted 2015 base salary.  Each of these predictors was significantly related to salary (F(3,1036) = 98.15, p < .001), and the combination of these predictors explained 22% of the variance in salary. After controlling for these variables, gender was added to the model to determine the extent to which it was predictive of salary above and beyond the known predictors of salary. Gender continued to significantly predict salary (F(4,1036)=75.33, p < .001); however, it only accounted for an additional 0.40% of the variance, indicating that gender may only explain a small portion of the variance in SIOP member salaries once other drivers of pay are taken into account.  (It’s worth noting that we did not include academic vs. practitioner in our analyses because it was found to have a low correlation (r = .09)).


Table 2

Summary of Hierarchical Regression Analysis Variable Predicting Salary





Step 1


Years of work experience in I-O psychology or related field




Number of employees managed or supervised




Master’s vs. PhD




Step 2


Years of work experience in I-O psychology or related field




Number of employees managed or supervised




Master’s vs. PhD








Note. R2 = .22 for Step 1; ΔR2 = .004 (p < .05).

*p < .05. **p < .01.


Likely due to the fact that the number of females in I/O psychology has increased steadily over time, males in our sample reported higher levels of experience than females (16.35 years for males; 13.13 years for females; t(1001.30)= 5.18, p < .001; d = 0.32). We therefore thought it important to determine the extent to which differences in work experience might explain the gender differences in pay. To investigate this, we tested the direct and indirect effects (through work experience) of gender on salary using the procedures suggested by Preacher and Hayes (2004). The relationship between gender and salary was partially mediated by years of work experience (CI95 for indirect effect:  -15,405.67, -6,245.01). The ratio of the indirect effect to the total effect was 0.49, suggesting that about 49% of the gender gap in salary can be explained by gender-based differences in experience. Figure 4 illustrates the standardized regression coefficients for individual paths. We did not test number of employees supervised or level of education as mediators because these variables were not significantly related to gender.


Figure 4. Work Experience Mediates the Effect of Gender on Salary

Note: Gender was coded as 1 = male, 2 = female.


In sum, it appears work experience is a key factor in explaining the gender pay gap for respondents to the 2016 SIOP Income and Employment Survey. Men, on average, have more years of work experience than women in the field. However, there remains an effect of gender on salary independent of work experience, as work experience only explained about half of the gender differences in salary.




The findings of this study are somewhat discouraging, as they indicate that there is a gender pay gap in I-O psychology even after controlling for years of work experience, number of employees supervised, and degree level. Previous research (e.g., Morgan, 2008) found that pay gaps were minimal between men and women with graduate degrees, and as most I-O psychologists have graduate degrees, the presence of a gender-based pay gap is somewhat surprising. All individuals included in the analysis were employed full time, so the gender pay gap cannot be explained by women opting for more part-time work than men. Additionally, the gender pay gap existed even after controlling for number of employees supervised (a proxy for authority, which was identified by Alkadry and Tower (2011) as a variable that partially explained the gender pay gap).


How, then, do we reduce the gender-based pay gap within I-O psychology? Some research suggests that women generally expect lower pay than do men (Hogue et al., 2010; Lips & Lawson, 2009), and coupled with women’s hesitancy to negotiate pay (Leibbrandt & List, 2015), this could lead to reduced pay among women in the field. Graduate advisors are often instrumental in helping their advisees land their first full-time I-O position, so graduate advisors could help mitigate the gender pay gap by encouraging their advisees of both genders to negotiate for higher pay when they receive their first job offer. Publications such as the SIOP Income and Employment Survey are also instrumental in helping early-career I-O psychologists develop realistic pay expectations, which can be informative during negotiations. Graduate program coordinators should ensure that their students are aware of such resources, and job seekers should use these resources to help them negotiate a salary appropriate to the position and the region.


The results of this study suggest an opportunity for future research into the pay gap between men and women in I-O psychology. A limited set of variables were examined in order to investigate the correlates of the gender pay gap, and past research suggests a number of fruitful possibilities for additional research. Variables not available in the salary survey, such as child and/or elder care responsibilities and likelihood of negotiating salary when approached with a job offer, should be considered in future research related to the pay gap in I-O psychology. As a field that advocates fair, equitable treatment for all employees in the workplace, the field of I-O psychology should set an example by thoroughly investigating the factors that lead to differing career outcomes for its members.




Alkadry, M. G., & Tower, L. E. (2011). Covert pay discrimination: How authority predicts pay differences between men and women. Public Administration Review, 71, 740.750. doi: 10.1111/j.1540-6210.2011.02413.x


American Association of University Women. (2017). The simple truth about the gender pay gap. Retrieved from 


DuVernet, A., Poteet, M., Parker, B., Conley, K., & Herman, A. (2017, January). Overview of results from the 2016 SIOP income & employment survey. The Industrial-Organizational Psychologist. Retrieved from


Goldin, C., Kerr, S. P., Olivetti, C., & Barth, E. (2017). The expanding gender earnings gap: Evidence from the LEHD-2000 census. American Economic Review: Papers and Proceedings, 107, 110-114. doi: 10.1257/aer.p20171065


Hogue, M., DuBois, C. L. Z., & Fox-Cardamone, L. (2010). Gender differences in pay expectations: The roles of job intention and self-view. Psychology of Women Quarterly, 34, 215-227. doi: 10.1111/j.1471-6402.2010.01563.x


Leibbrandt, A., & List, J. A., (2015). Do women avoid salary negotiations? Evidence from a large-scale natural field experiment. Management Science, 61, 2016-2024. doi: 10.1287/mnsc.2014.1994


Leslie, L. M., Manchester, C. F., & Dahm, P. C. (2017). Why and when does the gender gap reverse? Diversity goals and the pay premium for high potential women. Academy of Management Journal, 60, 402-432. doi: 10.5465/amj.2015.0195


Lips, H., & Lawson, K. (2009). Work values, gender, and expectations about work commitment and pay: Laying the groundwork for the “motherhood penalty?” Sex Roles, 61, 667-676. doi: 10.1007/s11199-009-9670-0


Morgan, L. A. (2008). Major matters: A comparison of the within-major gender pay gap across college majors for early-career graduates. Industrial Relations, 47, 625-650. doi: 10.1111/j.1468-232X.2008.00538.x


Poteet, M. L., Parker, B. N., Herman, A. E., DuVernet, A., & Conley, K. M. (2017). Society for Industrial and Organizational Psychology (SIOP) 2016 salary survey. Retrieved from


Preacher, K. J., & Hayes, A. F. (2004). SPSS and SAS procedures for estimating indirect effects in simple mediation models. Behavior Research Methods, Instruments, and Computers, 36, 717-731.


Proctor, B. D., Semega, J. L., & Kollar, M. A. (2016). Income and poverty in the United States: 2015. U.S. Census Bureau, Current Population Reports (P60-256(RV)). Retrieved from


Veira, X. Gonzalez. (2017, October 26). Can we talk about the gender pay gap? The Washington Post. Retrieved from:


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