Table 4.

Estimation of Cohen's k (1960) and Spearman's rho for the answer to the ESPAD‐Italia® 2004 questionnaire about lifetime use of cigarettes, alcohol, cannabis, tranquillizers or sedatives, hallucinogens, cocaine, ecstasy, alcohol mixed with pills, alcohol mixed with marijuana/hashish (ordinal answers) in test–retest study

Questions	N		Value	Standard error	Approximate T	Prob > T
Cigarette use	481	k unweighted	0.7249	0.0230	31.52	0.0000
		k weighted	0.8847	0.0358	24.68	0.0000
		Spearman' rho	0.9446	0.0082	62.97	0.0000
Drunkenness	479	k unweighted	0.5525	0.0254	21.77	0.0000
		k weighted	0.7032	0.0304	23.17	0.0000
		Spearman' rho	0.8048	0.0241	29.61	0.0000
Cannabis	470	k unweighted	0.6168	0.0261	23.62	0.0000
		k weighted	0.8009	00366	21.90	0.0000
		Spearman' rho	0.8547	0.0230	35.62	0.0000
Tranquillizers or sedatives	474	k unweighted	0.5960	0.0315	18.93	0.0000
		k weighted	0.4724	0.0315	15.01	0.0000
		Spearman' rho	0.2453	0.0825	5.503	0.0000
Hallucinogens	473	k unweighted	0.5320	0.0290	18.38	0.0000
		k weighted	0.5436	0.0349	15.58	0.0000
		Spearman' rho	0.6889	0.0667	20.63	0.0000
Cocaine	475	k unweighted	0.4121	0.0287	14.37	0.0000
		k weighted	0.4174	0.0341	12.23	0.0000
		Spearman' rho	0.5297	0.1065	13.58	0.0000
Ecstasy	474	k unweighted	0.3480	0.0309	11.26	0.0000
		k weighted	0.3421	0.0315	10.87	0.0000
		Spearman' rho	0.4680	0.0975	11.50	0.0000
Alcohol with pills	473	k unweighted	0.3994	0.0281	14.23	0.0000
		k weighted	0.4626	0.0326	14.18	0.0000
		Spearman' rho	0.5733	0.0932	15.18	0.0000
Alcohol mixed with marijuana/hashish	475	k unweighted	0.5184	0.0266	19.46	0.0000
		k weighted	0.6952	0.0357	19.47	0.0000
		Spearman' rho	0.7222	0.0376	22.71	0.0000