*3.1. Data Collection*

The database used in this paper is that in [7]. The sample has 402 answers from people over 20 years old from Spain, with a university degree and at least basic skills on Internet. The survey was answered between August 1 and September 10 2018. The responses are distributed between men and women as 53/47. In [7] it is outlined that this rate is due to the later incorporation in Spain of women to higher education. The composition of sample by ages is depicted in Figure 1. In [7] it is stated that this distribution is in accordance to

the age configuration of Spanish population. So, as we expected, the greater proportion of answers come from people between the ages of 41 and 50. Notice that individuals under 21 years old were not included because usually they have already not obtained a university degree. Arias-Oliva et al. in [7] point out that these patterns are similar to the distribution of the Spanish population and so, the sample is adequate to represent target population.

**Figure 1.** Sample distribution by age.

Figure 2 shows the distribution of net monthly household income. In [7] it is checked that this distribution implies a higher average income than those for whole Spanish population. However, this fact is not surprising since our survey was answered by collegeeducated people, who are more likely to earn higher salaries.

**Figure 2.** Sample distribution by monthly household income.
