Variable Household Income group Mother’s educational level Father’s educational level * Statistically significant Belief in efficacy of CSS in reducing fatal traffic injuries To some extent Jarahi et al. BMC Public Health 2011, 11:281 http://www.biomedcentral.com/1471-2458/11/281 Page 4 of 6 Table 3 Relationship of parents’ characteristics with their being/not being willing to pay for child safety seats (CSS) in logistic regression model Categories Low Moderate High Negative Positive Don’t know Lower than high school certificate High school certificate(diploma) Bachelor (BS/BA) Master(MS/MA) or above Lower than high school certificate High school certificate(diploma) Bachelor (BS/BA) Master(MS/MA) or above Number of Cases 274 193 51 39 147 278 54 62 191 240 25 70 163 240 45 Odds Ratio 1(baseline) 5.336 16.26 1(baseline) 1.04 3.21 0 0.9 1.3 1.08 0.18 0.34 0.27 1(baseline) 1(baseline) - - - - 0.95 Confidence Interval 2.33-12.23 5.81-45.46 0.25-4.33 0.25-4.33 0.89-11.53 0.24-3.38 0.33-5.17 0.19-6.17 0.05-0.63 0.1-1.41 0.06-1.21 P value < 0.001* < 0.001* < 0.001* 0.016* 0.96 0.07 0.98 0.84 0.87 0.71 0.93 0.57 0.007* 0.08 0.088 example providing free of charge or subsidized seats, rent- ing or health insurance coverage should be considered as options. In a study using WTP to assess public preferences towards fortification of foodstuffs with folic acid, 11 per- cent were willing to pay, 16% had zero WTP and 51% wanted their insurance to pay for it [15]. Nine per cent of the respondents estimated the pre- ventive effect of safety seats in RTCs to be nil or trifle. In this subgroup, the low perceived efficacy can at least partially explain their low WTP amount. In a research studying parental WTP for improving pedestrian safety, some parents did not want to participate in the pro- gram; because they did not believe that the program would be effective [8]. Our study showed that the amount of money that par- ents were willing to pay for car safety seats was asso- ciated with educational and economic status of the household. Other reports from Turkey and the US have also shown parents of higher socio-economic class to have higher WTP [18,8]. Using a contingent valuation questionnaire, Mataria et al, have also demonstrated that WTP for “luxury” quality attributes is negatively affected by both income-dependent and income-inde- pendent impoverishment [12]. One fifth of families reported past history of RTCs; but, we did not detect any significant relationships between this experience and their WTPs. Further research is necessary to explore the association of per- ceived risk of injury and WTP for safety seats. In addition, WTP was not associated with the number of children in the family. This might have been at least partially due to the high prevalence of one-child families in our sample. There was no relationship between par- ental WTP and child gender. This is generally in line with gender equity in receiving health care services for children in Iran. In our sample less than a third of parents had received any advice about use of safety seats. In a similar study in Turkey, 72% of parents were informed about the safety seats [18]. Moreover, the source of advice in our research was mostly from relatives and lay people, and then from the media, and only 4% reported receiving advice from physicians. Similarly in Turkey, the main source of parents’ information about safety seats was relatives or friends and only 3% from physicians [18]. Public campaigns to increase knowledge of people about safety seats are necessary. Future research should elabo- rate knowledge and attitudes of family physicians and pediatricians about safety seat utilization. There were potential sources of strategic, information and interviewer bias in our study. Strategic bias is when the participants guess that the results of the study are to be used for decision making and feel that it is in their interest to give a lower or higher valuation than the true value [21]. For reducing information and interviewer bias, we had set a fixed pictorial scenario, fixed scenario sentence, and pictures of safety seats in the questionnaire.