Variable	Modality	Stress resistance test category			Total	Khi-2	p-value
Variable	Modality	Low	Moderate	High
Gender	Male	7	38	5	50	0.39	0.82(ns)
Gender	Female	7	36	7	50	0.39	0.82(ns)
Total		14	74	12	100
Age	<30 ans	11	47	5	63	3.84	0.05*
Age	>30 ans	3	27	7	37	3.84	0.05*
Total		14	74	12	100
Socio-economic level	Average	11	52	12	75	7.85	0.02*
Socio-economic level	Good	3	22	0	25	7.85	0.02*
Total		14	74	12	100