Height and cognitive functions

There is broad evidence about the relationship between height and educational attainment on one side, and cognitive functions on the other (Tanner, 1989; Kretchmer et al., 1996; Case and Paxson, 2006).¹¹ Evidence from our sample confirms previous finding. In table 2 we show the relationship between height and years of education by gender and macro-area. In particular, we compare mean heights for low- and high-education groups where these groups are defined according to the years of education with respect to the median. There is a clear gradient in height as people in the high-education group are systematically taller than the other group.¹²

We also find a positive association between height and cognitive abilities.

10 The questions about numeracy skills in the survey are the following: 1) If the chance of getting a disease is 10 per cent, how many people out of 1,000 (one thousand) would be

expected to get the disease? 2) In a sale, a shop is selling all items at half price. Before the sale, a sofa costs 300. How much will it cost in the sale? 3) A second hand car dealer is selling a car for 6,000. This is two-thirds of what it costs new. How much did the car cost new? 4) Let's say you have 2000 in a savings account. The account earns ten per cent interest each year. How much would you have in the account at the end of two years?

11 See Case and Paxson (2006) for an exhaustive review of the literature.

12 The estimation of an exploratory model of the type education = α + β height +ε controlling also for gender, age and age squared, shows that the association between height and educational attainment is stronger in Mediterranean countries (β = 0.14) than in Nordic (β = 0.05) or Continental countries (β = 0.08).

Table 2. Mean height (in cm) by educational attainment Country Low

education High

education Observations Low

education High

education Observations

Men Women

Denmark 176.3 178.8 763 164.0 166.0 932 Sweden 176.1 178.5 1,391 163.8 165.1 1,613 Netherlands 176.0 178.9 1,350 164.4 167.3 1,579 Austria 173.3 176.7 780 162.8 164.1 1,105 Switzerland 172.9 175.7 445 160.4 164.0 525 Belgium 172.7 174.9 1,723 161.1 163.3 2,075 Germany 172.0 177.1 1,372 162.7 165.1 1,618 France 170.7 174.5 1,344 159.8 161.7 1,765 Greece 170.3 174.1 1,242 159.6 163.9 1,645 Spain 166.3 170.1 988 156.0 160.8 1,396 Italy 166.2 172.2 1,130 158.6 161.4 1,423 Total 172.1 175.5 12,528 161.0 163.9 15,676 Note: Low and high education are defined in terms of the median of years of education.

In order to show that, we consider the scores on numeracy test which are ordered on the basis of five increasing values: score 1 is a “bad” outcome while score 5 is a “good” one. We calculated the average height for each of the five scores by country (fig. 3). The positive association between height and numeracy skill is clear: tall stature is associated with high scores in numeracy, while short stature is associated with poor performances. With the exception of Austrian men, differences in mean height between score 1 and score 5 are always statistically significant. This result is corroborated by the analysis of the other two tests on cognitive functions, namely memory and fluency. The correlation coefficient of height and memory scores is 0.218 for men and 0.216 for women;

for height and fluency is 0.266 for men and 0.217 for women, for all countries altogether. When we compare the correlation coefficients of height and cognitive tests for the three macro-areas the following pattern emerges: Reading table 3 horizontally one can see that the correlation coefficients in the Mediterranean countries are always larger than in the other two areas, both for men and women.

Therefore the established association between physical stature and educational attainment on one side, and numeracy skills on the other is confirmed in this data set. It is also important to note that there are considerable differences in the test performances between macro-areas and gender. In table 4 we report the

distribution of the results for numeracy following the scale of five values previously defined. The differences in performance are quite striking: the Mediterranean countries score significantly worse than the other two areas.

Among the male population, in Nordic and Continental countries circa 4 percent of the sample scored poorly in the numeracy test; in Mediterranean countries the share is above 10 percent. The proportion of people who scored “good” in Mediterranean countries (14 percent) is less than half of that of Nordic men (32 percent). A similar pattern can also be identified among females. Within each macro-area men perform significantly better than women in numeracy score.¹³

We also need to define when an individual can be considered short or tall.

Physical stature is a country-specific variable: An individual whose stature is 1.80m is considered tall in Italy but of average stature in North-European countries. In what follows, when not otherwise specified, we shall consider a person short when his/her stature is below the reference median, tall when above. The reference median is defined by country and gender.¹⁴

Table 3. Height and cognitive tests by gender and area Nordic

countries Continental

countries Mediterranean

countries Total Numeracy test

Men 0.165 0.162 0.258 0.261

Women 0.125 0.181 0.214 0.235

Fluency

Men 0.175 0.160 0.203 0.265

Women 0.125 0.142 0.136 0.217

Memory

Men 0.139 0.140 0.214 0.220

Women 0.106 0.153 0.202 0.216

Note: All the correlation coefficients are significant at 1% level.

13 We tested difference of means for all countries and found that men always outperform women.

14 We also used three height categories (short, medium, and tall) on the basis of number of standard deviation from the mean. The results illustrated throughout the article are valid also with such specification.

156 158 160 162 164 166 168 170 172 174 176 178 180

Height in cm

Netherlands Sweden Denmark Germany Austria Belgium Switzerland France Greece Italy Spain

Men

1 bad 2 3 4 5 good

150 152 154 156 158 160 162 164 166 168

Height in cm

Netherlands Sweden Denmark Germany Austria Belgium Switzerland France Greece Italy Spain

Women

Figure 3. Mean height by score on numeracy test

Table 4. Distribution of scores on numeracy test (percent) Score Macro-area

1 (bad) 2 3 4 5 (good) Total Nordic 3.96 Men 6.64 28.00 29.74 31.67 100 Continental 3.56 7.87 23.75 41.41 23.41 100 Mediterranean 10.58 14.73 33.93 26.62 14.14 100 Total 6.37 10.16 28.86 32.45 22.15 100

Women

Nordic 5.49 15.17 34.12 28.19 17.04 100 Continental 6.55 15.07 30.13 34.81 13.43 100 Mediterranean 16.69 26.14 31.91 18.93 6.33 100 Total 10.30 19.49 31.89 26.76 11.57 100 Source: see text.