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. 2023 Oct 30;33(Suppl 2):s44–s50. doi: 10.1136/tc-2022-057679

Table 5.

Results of regression of the decision to smoke and the number of cigarettes smoked per day

Decision to smoke Number of cigarettes smoked per day
IV probit Seemingly unrelated regression
Smoker Low-price brands High-price brands
Price of low-price brands per pack of 20 pieces (taka in 2015 prices) 0.091*** (0.012) 0.022** (0.009) 0.005 (0.006)
Price of high-price brands per pack of 20 pieces (taka in 2015 prices) 0.003 (0.008) 0.018*** (0.004) 0.003 (0.003)
Household income (taka in 2015 prices) 0.018*** (0.004) 0.039*** (0.007) 0.056*** (0.004)
Age (years) 0.005** (0.002) 0.045*** (0.010) 0.028*** (0.006)
Education (reference: illiterate)
1–8 years 0.202*** (0.055) 0.756** (0.356) 0.435* (0.224)
9 years or more 0.457** (0.193) 3.309*** (0.424) 2.138*** (0.268)
Occupation (reference: owner farmer)
Tenant farmer 0.173 (0.259) 1.371 (0.922) 0.227 (0.582)
Self-employed in non-farm agricultural activity 0.194** (0.090) 0.529 (0.471) 0.487 (0.297)
Self-employed in non-agricultural activity 0.132 (0.309) 0.507 (0.620) 0.039 (0.391)
Farm wage labourer 0.100 (0.176) 0.585 (0.967) 0.653 (0.610)
Non-farm agricultural wage labourer 0.076 (0.117) 0.138 (0.504) 0.186 (0.318)
Non-agricultural wage labourer 0.829*** (0.132) 2.748** (1.113) 1.568** (0.702)
Professional (eg, physician, engineer) 0.609*** (0.114) 1.608** (0.708) 2.632*** (0.447)
Managerial, administrative or clerking 0.635 (0.469) 0.835 (1.057) 0.371 (0.667)
Student 0.144 (0.118) 0.333 (0.696) 0.094 (0.439)
Unemployed 0.059 (0.308) 2.980** (1.220) 0.083 (0.770)
Housewife/housekeeper/household manager 0.270*** (0.061) 0.220 (0.426) 0.655** (0.269)
Resident of urban area (reference: rural area) 0.311*** (0.075) 2.556*** (0.295) 1.526*** (0.186)
Married 0.159 (0.189) 0.903** (0.379) 0.188 (0.239)
Number of friends who are smokers 0.020 (0.339) 0.654*** (0.107) 0.074 (0.067)
Number of observations 8148 5832

(1) The z statistics of the coefficients are in parentheses. (2) The levels of significance used are: *p<0.10, **p<0.05, ***p<0.01. (3) The χ2(2) statistics from the Wald test of exogeneity in the IV probit model using prices of low-price and high-price brands instrumented with composite housing index is 6.65 (p=0.0360), which rejects the null hypothesis of exogeneity of cigarette prices at a 5% level of significance. The full set of results including the instrumental variable estimation of cigarette prices is provided in the online supplemental table A2. (4) The validity of the instruments is tested using the F-statistics of the reduced form regression of cigarette prices of low-price and high-price brands on composite housing index and all other regressors in the IV probit model. The overall F-statistics is greater than 10, indicating that the instruments are strong and identifies the effect of the prices of low-price and high-price brands. The results of these regressions are provided in the online supplemental table A3.

IV, instrumental variable.