Table 6.

Correlation coefficients (r)¹ between test and retest of the SF-FFQ4PolishChildren questionnaire.

Variables (All in Points)	Range of Points	Children Aged 6–10 Years (n = 437)	Adolescents Aged 11–15 Years (n = 630)
		Parent (Test–Retest)	Adolescent (Test–Retest)	Adolescent (Test) & Parent (TestP)
Nutrition knowledge score 2	0–18	0.80	0.68	NA
pHDI	0–100	0.76	0.63	0.52
nHDI	0–100	0.83	0.68	0.53
Screen time score	0–5	0.78	0.58	0.45
Physical activity score	0–5	0.77	0.71	0.51
FAS	0–9	0.93	0.91	0.90

¹r—the Spearman’s rank correlation coefficient (all <0.05); nutrition knowledge score—evaluated based on 18 questions [22]; ² in a group of 6–10-year-old children, nutrition knowledge was assessed in their parents; pHDI—a pro-healthy diet index composed of four questions (dairy products, fish, vegetables, fruit) [22]; nHDI—a non-healthy diet index composed of four questions (fast food, sweetened soft drinks, energy drinks, sweets) [22]; screen time score—based on a single question with six response categories [22]; physical activity score—based on two questions: Physical activity at school and physical activity at leisure time [22]; FAS—the Family Affluence Scale composed of six questions [26]; NA—not applied.