Table 4.

Kruskal–Wallis test of selected sociodemographic factors and past month concurrent polysubstance use

Sociodemographic factors	N	Mean Rank	df	χ2	p value
Age group
12–17 years	26	452.58
18-34 years	395	482.34	3	33.479	0.000*
35-54 years	342	461.25
55-65 years	144	359.31
Education level
Primary or less	119	454.89
Secondary school	653	456.23	2	0.993	0.609
University	133	435.47
Occupational status
Professional	31	161.52
Skilled workers	437	290.18	3	35.262	0.000*
Unskilled workers	87	309.31
Armed forces	12	192.00
Total household income
less than $25,000	218	389.49
$25,001-$50,000	262	378.23
$50,001-$70,000	139	383.61	4	7.435	0.115
$70,001- $100,000	76	345.80
$120,000 or more	55	327.59

^* p < 0.01 level significance