Table B.2.
Self-perceived ABILITY: means (SD) for ages 9–16, by zygosity and sex; and ANOVA results showing significance and effect size.
| Enjoyment | Countries | School subjects | Zygosity
|
Sex
|
ANOVA
|
|||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| MZ | DZss | Female | Male | Zygosity
|
Sex
|
Zygosity * sex
|
||||||
| p | η2 | p | η2 | p | η2 | |||||||
| 9 years | UK | Math | −.07 (1.02) | .00 (1.01) | −.18 (.98) | .20 (1.01) | .01 | .00 | .00 | .03 | .02 | .00 |
| English | .02 (1.01) | −.01 (.99) | .17 (.95) | −.17 (1.04) | .58 | .00 | .00 | .03 | .02 | .00 | ||
| Science | .00 (1.00) | −.01 (.98) | −.05 (.98) | .07 (1.01) | .74 | .00 | .00 | .00 | .14 | .00 | ||
| Germany | Math | .05 (.98) | −.14 (.98) | −.17 (1.01) | .08 (.95) | .37 | .01 | .25 | .01 | .49 | .01 | |
| German | .12 (.88) | −.02 (.99) | .20 (.81) | −.13 (1.03) | .04 | .02 | .04 | .02 | .35 | .01 | ||
| 10 years | Canada (Quebec) | Math | .03 (1.03) | −.04 (.95) | −.03 (1.07) | .03 (.92) | .58 | .00 | .67 | .00 | .73 | .00 |
| Reading | .07 (1.01) | −.10 (.98) | .05 (.99) | −.05 (1.02) | .17 | .01 | .40 | .00 | .75 | .00 | ||
| Japan | Math | .11 (1.04) | −.16 (1.01) | −.10 (1.05) | .12 (1.00) | .10 | .02 | .35 | .01 | .33 | .01 | |
| 11 years | Germany | Math | −.01 (.95) | −.12 (.98) | −.26 (.99) | .14 (.90) | .43 | .01 | .22 | .01 | .05 | .02 |
| German | .01 (.92) | −.02 (.98) | .15 (.94) | −.17 (.96) | .83 | .00 | .66 | .00 | .44 | .01 | ||
| Japan | Math | .02 (1.04) | −.03 (.97) | −.15 (1.06) | .22 (.91) | .61 | .00 | .01 | .04 | .21 | .01 | |
| 12 years | UK | Math | −.01 (.99) | −.02 (.99) | −.08 (.97) | .10 (1.03) | .29 | .00 | .46 | .00 | .00 | .01 |
| English | .00 (.99) | .01 (.99) | .24 (.96) | −.24 (.98) | .35 | .00 | .00 | .05 | .17 | .01 | ||
| Science | −.03 (1.00) | .01 (.99) | −.02 (.98) | .03 (1.01) | .09 | .00 | .06 | .00 | .42 | .00 | ||
| Canada (Quebec) | Math | .06 (1.00) | −.07 (1.01) | −.02 (1.01) | .02 (.99) | .27 | .01 | .78 | .00 | .36 | .00 | |
| Reading | −.02 (.96) | .02 (1.05) | .06 (.98) | −.06 (1.03) | .74 | .00 | .22 | .01 | .07 | .01 | ||
| Japan | Math | −.07 (1.11) | .14 (.95) | −.05 (1.06) | .10 (1.07) | .55 | .00 | .77 | .00 | .08 | .02 | |
| USA | Reading | .04 (.63) | −.03 (.68) | .07 (.65) | −.09 (.68) | .20 | .00 | .04 | .01 | .26 | .00 | |
| 13 years | Germany | Math | .08 (.89) | −.11 (1.04) | −.20 (.94) | .16 (.97) | .26 | .01 | .21 | .01 | .55 | .01 |
| German | .16 (.86) | .03 (1.04) | .21 (.95) | −.07 (.99) | .00 | .04 | .02 | .02 | .30 | .01 | ||
| Japan | Math | .12 (1.00) | −.36 (.82) | −.28 (.93) | .37 (.92) | .01 | .06 | .00 | .09 | .68 | .00 | |
| 16 years | UK | Math | .02 (.99) | .03 (.99) | −.09 (1.03) | .14 (.94) | .26 | .00 | .01 | .06 | .11 | .00 |
| Japan | Math | −.04 (.98) | .02 (1.04) | −.15 (1.02) | .19 (1.00) | .54 | .00 | .09 | .03 | .72 | .00 | |
| Russia | Math | .08 (1.14) | −.02 (.81) | −.19 (1.06) | .19 (.97) | .33 | .01 | .16 | .02 | .66 | .02 | |
Note. The results were adjusted for exact age within each sample. DZss = same sex DZ twins.
Significant differences in zygosity, sex and sex * zygosity interaction are indicated in bold.