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Every year, the Department of Labor issues a report on the pay gap between women and men.
Women earn a median of $30,0001 per year, while men earn $40,000 per year. In other words, working women earn 75% of what men earn.
But this gap doesn’t take into account the fact that on average, men work more hours than women. According to U.S. census data, men spend an average of 41.0 hours per week at their jobs, while women work an average of 36.3 hours per week.
Many argue that gender discrimination explains a large part of the difference in earnings. Others argue that parenthood and gender roles usually affect women's earnings more than men.
To better understand the pay gap, we classified the respondents according to their marital and parenthood status2. The gap is dramatically higher between married couples versus singles without children. For married parents, the gap is even greater.
But we also found that married fathers work even more than other men, while married mothers work less than married women without kids.
We analyzed the pay gap across hundreds of U.S. occupations. According to our research, in most occupations, the main source of the pay gap lies in the difference between the number of hours spent at work by women and men, and marital status and parenthood explain almost all this difference in working times.
The different behavior of women and men3 has an impact on the gender wage gap. As we will see below, the decision of who does most of the work outside versus who stays at home influences the pay gap in two ways: it modifies the nominal income, but it also influences how much women and men earn per each hour worked4.
EXPLORE THE DIFFERENCES IN SALARY INCOME ACROSS OCCUPATIONS USING THE INTERACTIVE BELOW. VIEW THE FULL-SCREEN VERSION HERE.
Let's take a look at the most common occupation in the US: Managers. This occupation is representative of the overall trend we see in the United States.
Single male managers without kids earn a median of $60,000 per year, while single female managers without kids earn $58,000 per year. On average, single male managers work 43.7 hours per week, while single female managers work 42.3 hours per week.
This means that men earn 3.4% more but work 3.5% more hours per week.
But when we look at the pay gap between married couples, we see a different picture. Both female and male married managers do have a higher salary. But men earn much more than women.
Male married managers without kids earn a median of $90,000, while female married managers without kids earn a median of $62,000. A pay gap of 31%. In other words, women earn $0.69 for each dollar earned by their male counterparts.
A large part of this gap is explained by the number of hours spent at work. Men tend to work more after they marry. The average weekly working hours of males increase 4.3%, while women keep working the same quantity of hours per week. This explains a part of the gap increase.
But the time spent at work does not explain all of the gender pay gap. Married men managers without kids also earn more for each hour at work: they earn $38.40 per hour while married women without kids earn only $28.70. That means that for each hour spent at their jobs, male married managers without kids earn about 34% more than women. As we will see in detail below, the different hourly rate is related to job market trends.
We can see the same pattern across occupations like school teachers, secretaries, nurses, customer service representatives, and a lot of other professions: a small pay gap for singles without kids and a larger pay gap for married people.
We have seen that, for the most common occupations, there is almost no absolute pay gap for singles without kids, and this gap could be explained by the difference in time spent at work. But there are some occupations that do show a gap for this group of people.
Notable examples are drivers, retail salespersons, supervisors and janitors. Interestingly, we can see the same general pattern in these occupations: the uncontrolled gap increases dramatically for married couples, even if they do not have kids.
The same general pattern repeats itself in occupations where single women without kids earn more than their male counterparts. Some of them are secretaries, customer service representatives, cooks, stock clerks, office clerks and receptionists.
In all of these occupations, the pay gap in favor of women reverts if they marry: married men still earn more than married women.
Now, let’s look closely at the different hourly wages paid to women and men. The data shows that there is a persistent difference in the hourly rate earned by women and men, specially for married women and men. But the data also shows that men work more than women.
After taking a closer look at the data, we found a relationship between the hourly wage and the time spent at work. The average hourly pay increases as the number of hours worked per week increases. This is true for both sexes.
In the following chart, we plotted the hourly pay for women and men. To isolate the effect of marriage and parenthood, we took into account only singles without kids.
In the next chart, we can see the average number of hours worked for each group:
For the relevant range of hours worked per week, the average hourly pay increases as the time spent at work increases.
Because men tend to work more hours than women, especially if they are married, and even more if they are married parents, this could explain a large portion of the pay gap.
Also, the previous chart shows that on average, single women without kids are getting paid more than men for every hour spent at work. This could mean that if women worked the same amount of hours as men do, and other conditions remained the same, there would be no pay gap for this group5.
It is important to note that age and job experience are also relevant factors in the gender gap debate. To isolate the possible effects that age and job experience may have in the pay gap for each of the different groups, we plotted the weighted average of working hours per age for single women and men without kids.
For singles without kids, there is a very small gap at every age. But for married couples, there is a significant gap in working hours at every age.
If we take into account how the hourly wage varies as men and women get older, the hourly wage of men increases more than the hourly wage of women. The same pattern can be seen in all three groups.
The charts above demonstrate that job experience is correlated with the time spent at work through the years. As years pass, men accumulate more practice and training than women. The job market pays more if the worker has more experience. In other words, the gap widens as men acquire more experience than women.
In this article, we found that one of the main sources of the gender pay gap is the fact that, on average, women and men devote a different number of hours to their jobs, specially after marriage and parenthood.
The literature on gender pay gap is very extensive. Different papers focus on diverse causes to explain it. Two of the most mentioned reasons are gender discrimination and motherhood and gender roles.
Gender discrimination against women occurs if a woman is paid less than a man for doing the same job.
If we consider that the quantity of hours devoted to a job determines whether we consider a job to be the same as another, the data doesn’t support the idea of gender discrimination at the aggregate level.
The hourly pay rate for married women is lower than for married men on average, but a probable explanation is because the job market pays less per hour if the number of hours worked decreases, and married women tend to work less. The same pattern can be seen in almost every occupation.
Also, men tend to devote more time to work, thus acquire more experience as years pass by, and the job market pays more if the worker has more experience.
This doesn’t mean that gender discrimination doesn’t exist. Our analysis just shows that, at the aggregate level, most of the gap is not explained by gender discrimination.
Regarding the second aspect of the pay gap, societal ideas of gender roles influence the behavior of women and men. Also, biological factors related to parenthood do play a role in the creation of differences in preferences. Namely, women get pregnant and women breastfeed. These differences between sexes could be a plausible explanation of why women tend to spend more time at home versus their couples, especially after marriage and parenthood6.
To conclude and to recap, we can say that, according to our analysis, job market forces and gender preferences in relation to marital status and parenthood could explain almost all of the pay gap. Most of the gap is not the result of gender discrimination.
This analysis uses microdata from U.S. Census Bureau American Community Survey (ACS) 2017, extracted using IPUMS USA service7.
Hourly wage average is our own calculation using the total pre-tax wage and salary income and the number of hours per week that the respondent usually worked.
We also removed a small number of respondents from our database that we considered not representative, namely people with an hourly wage higher than $900 per hour and less than $3 per hour.
Also, to isolate any possible effect caused by marked differences between women and men when they reach older ages, we took into account only people younger than 70 years old.
We used Python and R to aggregate and process the data. The final figures are the result of an extensive research process and various tests. If you come across an error or mistake, please do not hesitate to contact us below.
Median pre-tax wage and salary income. Only working people younger than 70. Not filtering out any outlier, for the rest of the article we filtered out cases that we consider abnormal and not representative. See the methodology section for more information.
To isolate the effect of parenthood and marital status, we took into account only three groups: Not married without children, married without children and married with children. Further research could also take into account more categories, like single parents.
Different choices can be agreed upon and voluntary decisions of both members of the couple, although influenced by sociological aspects and gender roles.
To calculate the hourly pay, we used the average number of hours per week that the respondent usually worked.
Or a small gap in favor of women.
Also, not plotted here, the difference in worked hours slightly increases as men and women get older.
These can be agreed and voluntary decisions of both member of the couple, although, influenced by sociological aspects and gender roles.
Steven Ruggles, Sarah Flood, Ronald Goeken, Josiah Grover, Erin Meyer, Jose Pacas, and Matthew Sobek. IPUMS USA: Version 8.0 [dataset]. Minneapolis, MN: IPUMS, 2018. https://doi.org/10.18128/D010.V8.0
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