This gives rise to the question of how personality traits influence the frequency of sex

Previous research has shown that the frequency of sex plays a role in happiness (Blanchflower and Oswald 2004; Cheng and Smyth 2015; Schmiedeberg et al. 2017). Table 5 shows the key results of a random effects GLS regression on the determinants of frequency of intercourse per month. As a check of robustness, we also present a random effects interval regression using the initial categories for the frequency of sex. For the interval regression, we translated the interval boundaries shown in Appendix Table 10 into the frequency of intercourse per month.

The interval regression and the linear regression on the midpoints of the intervals yield very similar results. While the variable for agreeableness does not take a significant coefficient, the other four personality traits emerge as significant determinants. Extraversion, openness to experience, and conscientiousness are positively associated with the frequency of intercourse. Neuroticism is negatively linked to the frequency of intercourse. To provide a quantitative illustration, a one standard increase in the neuroticism score implies a decrease in the monthly frequency of intercourse by almost half a day. Taking into account that the average frequency is about 6 days per month, this is an 8 percentage decrease in the frequency of intercourse.

So far, we have considered the actual frequency of sex. We recognize that the desired frequency of sex ; Smith et al. 2011). Thus, using a multinomial logit approach, we estimate the determinants of desiring much less frequent, somewhat less frequent, somewhat more frequent, or much more frequent sex. The reference group consists of persons who are satisfied with the actual frequency of intercourse. Table 6 provides the key results. Only a few of the results are significant. Extraversion is significantly associated with a higher likelihood of desiring much more frequent sex. Conscientiousness is significantly linked with a lower probability of desiring much less frequent sex. Neuroticism is significantly associated with both a higher likelihood of desiring much less frequent sex and a higher likelihood of desiring somewhat more and much more frequent sex. The estimations show no significant influence of agreeableness and openness.

Extradyadic affairs

Finally, we examine the role of personality traits in having extradyadic affairs during the last 2 years. This gives insights into how personality influences a person’s commitment to the partner. Table 7 shows the key results of a random effects logit estimation. Since the share of observations with extradyadic affairs is at 3% relatively low, the table also presents Firth’s logit estimation as a robustness check. Footnote 10 The random effects regression and Firth’s model yield very similar results. While openness to experience does not emerge as a significant determinant, the variables for the other four personality traits take significant coefficients. While extraversion and neuroticism are significantly positive determinants of extradyadic affairs, conscientiousness and agreeableness are significantly negative determinants. For a quantitative illustration, let us consider a one standard deviation increase on the scale for conscientiousness. This increase is associated with a 0.7 percentage point lower likelihood of having extradyadic affairs. Given that there are 3% of observations with extradyadic affairs, this implies a change in the likelihood by about 23%.

Further estimations

We performed a series of further estimations to check the robustness of the results. Footnote 11 One robustness check focused on the minimum age of persons in our estimation sample. The findings presented in this study are based on an estimation sample of persons who are at least 18 years old. One may ask if the results are influenced by younger persons whose personalities might still be forming. Thus, as a robustness check, we excluded younger persons and ran the regressions only for those who are at least 25 years old. This exercise yielded a very similar pattern of key results.