Cross-sectional analysis of smoking behaviors

694 The Journal of Human Resources of the late 1990s that the real price to consumers increased substantially. Figure 2 indicates that most of the differential in smoking prevalence by educational level is already present before the early 1980s and has occurred when there was no large variation in the real price of cigarettes. Finally, it is worth emphasizing that this data set of smoking histories is based on self-reported smoking behaviors. This limitation of the data is difficult to avoid, especially in an historical context. It would potentially bias the results if more edu- cated individuals were more or less likely to report truthfully their smoking practices. I am not aware of evidence that this would be the case.

III. Cross-sectional analysis of smoking behaviors

Farrell and Fuchs 1982 use the age pattern of smoking initiation to show that “the strong negative relation between schooling and smoking observed at age 24 is accounted for by differences in smoking behavior at age 17, when all subjects were all in the same grade.” 13 Using the data set constructed for this paper, I replicated results similar to those obtained by Farrell and Fuchs 1982 for each ten-year birth cohort between 1910 and 1979. The model is: S ⳱ ␣CⳭ␤XⳭε 1 a a Where: a is age and goes from 17 to 60 according to the regression. S is a dummy for whether the individual smokes at age a. C is a time-invariant dummy for whether or not the individual is a college graduate. At age 17, it represents future college status and, as in Farrel and Fuchs 1982, it takes the value 1 for future college graduates. X are other time-invariant covariates: gender, race, year of birth, and survey year. Read horizontally, Tables 1 and 2 follow smoking behavior at a particular age, across birth cohorts while read vertically, the tables follow the same birth cohort across different ages. I focus on college education for two reasons. College gradu- ation is the crucial margin for smoking prevalence, as evidenced in Figure 2. It also will allow me to compare Tables 1 and 2 with Tables 3 and 4 where I will consider a series of panels following smoking behavior before and after college graduation. The results are included in Table 1 for males and Table 2 for females. In the first two rows of Tables 1 and 2, 14 the dependent variable is whether the individual was 13. Notice that the sample used in Farrell and Fuchs 1982 is not nationally representative as it is drawn from four small California cities. 14. Notice that in Tables 1 and 2 as well as in Tables 3 and 4, I have excluded the data from the 1983, 1985, 1990, 1991, and 1994 National Health Interview Surveys because the age at smoking initiation, a necessary variable for the analysis in those tables, was not included in the questionnaires. de Walque 695 Table 1 The effect of college education on smoking behavior at different ages. Males. Cross-sectional linear regressions Dependent variable: smoked at ages 17 to 60 Birth Cohort 1910–19 1920–29 1930–39 1940–49 1950–59 1960–69 1970–79 At age 17 College ⳮ 0.146 ⳮ0.151 ⳮ0.179 ⳮ0.191 ⳮ0.182 ⳮ0.181 ⳮ0.178 [0.0119] [0.0087] [0.0078] [0.0059] [0.0048] [0.0052] [0.0116] Observations 8,929 14,728 15,847 22,326 27,829 19,405 4,374 At age 25 College ⳮ 0.095 ⳮ0.105 ⳮ0.149 ⳮ0.178 ⳮ0.209 ⳮ0.227 ⳮ0.191 [0.0142] [0.0096] [0.0087] [0.0067] [0.0057] [0.0062] [0.0143] Observations 8,929 14,728 15,847 22,326 27,829 19,405 4,374 At age 30 College ⳮ 0.092 ⳮ0.098 ⳮ0.149 ⳮ0.189 ⳮ0.210 ⳮ0.240 [0.0141] [0.0096] [0.0117] [0.0066] [0.0059] [0.0078] Observations 8,929 14,728 15,847 22,202 24,281 12,879 At age 35 College ⳮ 0.105 ⳮ0.107 ⳮ0.156 ⳮ0.189 ⳮ0.212 ⳮ0.260 [0.0141] [0.0097] [0.0087] [0.0068] [0.0066] [0.0123] Observations 8,929 14,728 15,847 20,131 18,905 5,277 At age 40 College ⳮ 0.108 ⳮ0.111 ⳮ0.160 ⳮ0.183 ⳮ0.229 [0.0141] [0.0098] [0.0086] [0.0071] [0.0083] Observations 8,929 14,728 15,758 17,344 11,995 At age 45 College ⳮ 0.119 ⳮ0.124 ⳮ0.160 ⳮ0.178 ⳮ0.232 [0.0140] [0.0096] [0.0087] [0.0081] [0.0138] Observations 8,929 14,728 14,272 13,215 4,461 At age 50 College ⳮ 0.108 ⳮ0.126 ⳮ0.157 ⳮ0.190 [0.0137] [0.0094] [0.0087] [0.0102] Observations 8,929 14,652 12,259 8,381 continued 696 The Journal of Human Resources Table 1 continued Dependent variable: smoked at ages 17 to 60 Birth Cohort 1910–19 1920–29 1930–39 1940–49 1950–59 1960–69 1970–79 At age 55 College ⳮ 0.111 ⳮ0.118 ⳮ0.151 ⳮ0.185 [0.0132] [0.0093] [0.0094] [0.0171] Observations 8,929 13,156 9,585 2,995 At age 60 College ⳮ 0.109 ⳮ0.105 ⳮ0.147 [0.0123] [0.0090] [0.0113] Observations 8,857 11,084 6,191 Analysis from smoking histories from the 1978, 1979, 1980, 1987, 1988, 1992, 1995, 1997, 1998, 1999 and 2000 National Health Interview Surveys for individuals age 17 and older at the time of the survey. At age 17, the individual is assigned his future college graduation status. Smoking histories are recon- structed using the age at smoking initiation and cessation. See also Note 5. Additional controls include gender, year of birth, race, and survey year dummies. Robust standard errors in square brackets. , , denote statistical significance at the 1 percent, 5 percent, and 10 percent confidence levels, respectively. smoking at age 17 and at age 25. At age 17, the individuals is assigned, as in Farrell and Fuchs 1982 his or her future college graduation status. For males in Table 1, at age 25, when educational achievements can be considered as definitive, there is a clear negative effect of college graduation on smoking prevalence. This effect increases for younger birth cohorts. But, at age 17, before college enrollment, when males are classified according to their future definitive schooling levels, the strong negative relationship between college and smoking is already present. 15 Similarly, for females in Table 2, the negative gradient between education and smoking is also already present at age 17 except for the cohort born between 1910 and 1919 for which the coefficient is insignificant. 16 Farrel and Fuchs 1982 use the existence 15. Actually, for males, the magnitude of the gradient is larger at age 17 than at age 25 for the birth cohorts born before 1950. This might indicate that individuals who will end up less educated start smoking sooner and that those who will become more educated are more likely to start later, between ages 17 and 25. This is confirmed in the two last rows of Table 3: Among males, future college graduates tend to start smoking later. 16. For females, it is also the case that up to the birth cohorts born after 1960, the coefficient is more negative when the analysis is done at age 17, using future education levels, than at age 25 using achieved education levels. For the birth cohort born between 1920 and 1929, the coefficient even switches sign, from negative to positive, between the analysis at age 17 and at age 25. College-educated women born after 1939 tended to start smoking later than women with no college degree see bottom of Table 4, so this could explain this phenomenon, as for males. However, among women born before 1940, college graduate started earlier. Therefore, “late” smoking initiation cannot be an explanation for those birth co- horts. Notice that most women born between 1910 and 1940 were 17 and 25 before the information about the dangers of smoking was available. de Walque 697 Table 2 The effect of college education on smoking behavior at different ages. Females. Cross-sectional linear regressions. Dependent variable: smoked at ages 17 to 60 Birth Cohort 1910–19 1920–29 1930–39 1940–49 1950–59 1960–69 1970–79 At age 17 College ⳮ 0.001 ⳮ 0.028 ⳮ0.044 ⳮ0.083 ⳮ0.116 ⳮ0.146 ⳮ0.127 [0.0073] [0.0063] [0.0064] [0.0046] [0.0040] [0.0046] [0.0098] Observations 16,005 21,141 20,152 27,315 35,300 25,120 5,645 At age 25 College 0.022 0.019 ⳮ 0.028 ⳮ0.075 ⳮ0.145 ⳮ0.184 ⳮ0.157 [0.0114] [0.0101] [0.0090] [0.0064] [0.0051] [0.0055] [0.0115] Observations 16,005 21,141 20,152 27,315 35,300 25,120 5,645 At age 30 College 0.021 0.012 ⳮ 0.050 ⳮ0.095 ⳮ0.156 ⳮ0.199 [0.0118] [0.0102] [0.0090] [0.0064] [0.0051] [0.0068] Observations 16,005 21,141 20,152 27,179 30,817 16,579 At age 35 College 0.013 ⳮ 0.001 ⳮ 0.071 ⳮ0.109 ⳮ0.156 ⳮ0.219 [0.0117] [0.0102] [0.0088] [0.0064] [0.0057] [0.0106] Observations 16,005 21,141 20,152 24,725 23,583 6,742 At age 40 College 0.005 ⳮ 0.009 ⳮ 0.083 ⳮ0.123 ⳮ0.169 [0.0117] [0.0101] [0.0086] [0.065] [0.0072] Observations 16,005 21,141 20,049 21,357 14,667 At age 45 College ⳮ 0.009 ⳮ 0.018 ⳮ 0.092 ⳮ0.136 ⳮ0.178 [0.0115] [0.0099] [0.0086] [0.0073] [0.0114] Observations 16,005 21,141 18,272 16,430 5,438 At age 50 College ⳮ 0.014 ⳮ 0.019 ⳮ0.089 ⳮ0.145 [0.0113] [0.0098] [0.0087] [0.0090] Observations 16,005 21,055 15,818 10,509 continued 698 The Journal of Human Resources Table 2 continued Dependent variable: smoked at ages 17 to 60 Birth Cohort 1910–19 1920–29 1930–39 1940–49 1950–59 1960–69 1970–79 At age 55 College ⳮ 0.018 ⳮ0.025 ⳮ0.086 ⳮ0.141 [0.0109] [0.0097] [0.0094] [0.0148] Observations 16,005 19,294 12,513 3,823 At age 60 College ⳮ 0.026 ⳮ0.035 ⳮ0.090 [0.0103] [0.0094] [0.0112] Observations 15,913 16,769 8,152 Analysis from smoking histories from the 1978, 1979, 1980, 1987, 1988, 1992, 1995, 1997, 1998, 1999 and 2000 National Health Interview Surveys for individuals age 17 and older at the time of the survey. At age 17, the individual is assigned her future college graduation status. Smoking histories are recon- structed using the age at smoking initiation and cessation. See also Note 5. Additional controls include gender, year of birth, race, and survey year dummies. Robust standard errors in square brackets. , , denote statistical significance at the 1 percent, 5 percent, and 10 percent confidence levels, respectively. of a negative gradient between future college graduation and tobacco use at age 17 as ground to reject the causality from schooling to smoking, in favor of a “third variable” hypothesis. However, they do not analyze smoking behavior after age 24. Tables 1 and 2 present, by birth cohort, a cross-sectional analysis of smoking be- havior at a large range of ages 17 to 60. The remainder of the analysis now focuses on smoking behaviors between ages 25 and 60. 17 In Table 1 for males, all coefficients on college education are negative and significant. The general trend is for them to increase in magnitude horizontally indicating that the younger the birth cohort, the stronger the negative effect of edu- cation on smoking for a certain age. Among cohorts born later in the 20th century who have been more exposed to information, the effect of college education seems to be stronger. The analysis for females is in Table 2. The magnitude of the coefficients is smaller among females than males. For females born between 1910 and 1919 at ages 25 and 30 and those born between 1920 and 1929 at age 25, the coefficient on college status is positive and significant. Before the information on the dangers of smoking was available, more educated women were more likely to smoke. 18 For those two birth cohorts, at older ages, the coefficient on college is not statistically different 17. Tables 1 and 2 use a linear regression model, but Tables A1 and A2 confirm the results using a logit model, displaying the marginal effects of the logit coefficients. 18. But as described above, this was not always the case at age 17, when future college graduation status was considered. de Walque 699 Table 3 The effect of college education on smoking behavior at different ages. Panel data with fixed effects, linear model. Males Dependent variable: smoked at age 17 and smoked at ages 25 to 60 1 2 3 4 5 6 7 Birth cohort 1910–19 1920–29 1930–39 1940–49 1950–59 1960–69 1970–79 At age 25 College 0.047 0.041 0.024 0.005 ⳮ 0.030 ⳮ 0.045 ⳮ 0.014 [0.0140] [0.0097] [0.0084] [0.0066] [0.0053] [0.0054] [0.0130] Observations 17,858 29,456 31,694 44,652 55,658 38,810 8,748 At age 30 College 0.048 0.046 0.023 ⳮ 0.007 ⳮ 0.038 ⳮ 0.043 [0.0145] [0.0100] [0.0089] [0.0069] [0.0058] [0.0074] Observations 17,858 29,456 31,694 44,404 48,562 25,758 At age 35 College 0.033 0.036 0.016 ⳮ 0.012 ⳮ 0.041 ⳮ 0.050 [0.0148] [0.0103] [0.0092] [0.0073] [0.0068] [0.0125] Observations 17,858 29,456 31,694 40,262 37,810 10,554 At age 40 College 0.029 0.031 0.012 ⳮ 0.011 ⳮ 0.050 [0.0146] [0.0106] [0.0095] [0.0078] [0.0091] Observations 17,858 29,456 31,516 34,688 23,990 At age 45 College 0.017 0.017 0.006 ⳮ 0.001 ⳮ 0.047 [0.0149] [0.0107] [0.0100] [0.0093] [0.0159] Observations 17,858 29,456 28,544 26,430 8,922 At age 50 College 0.027 0.015 0.0007 0.010 [0.0149] [0.0107] [0.0106] [0.0124] Observations 17,858 29,304 24,518 16,762 At age 55 College 0.024 0.0159 0.009 0.005 [0.0148] [0.0111] [0.0120] [0.0224] Observations 17,858 26,312 19,170 5,990 continued 700 The Journal of Human Resources Table 3 continued Dependent variable: smoked at age 17 and smoked at ages 25 to 60 1 2 3 4 5 6 7 Birth cohort 1910–19 1920–29 1930–39 1940–49 1950–59 1960–69 1970–79 At age 60 College 0.028 0.027 0.021 [0.0145] [0.0116] [0.0158] Observations 17,714 22,168 12,382 Average age at smoking initiation for smokers College 19.14 18.45 18.60 18.35 18.38 18.52 18.16 Not college 17.50 17.14 16.92 16.91 17.13 17.01 16.74 Analysis from smoking histories from the 1978, 1979, 1980, 1987, 1988, 1992, 1995, 1997, 1998, 1999, and 2000 National Health Interview Surveys for individuals age 25 and older at the time of the survey. Smoking histories are reconstructed using the age at smoking initiation and cessation. See also Note 5. Panel linear regressions with individual fixed effects: the baseline smoking behavior is always taken at age 17. College always takes the value 0 at age 17. At ages 25 and older, it takes the value 1 for college graduates and the value 0 otherwise. Age is controlled for. Robust and clustered standard errors in square brackets. , , denote statistical significance at the 1 percent, 5 percent, and 10 percent confidence levels, respectively. than zero. From age 55 for women born in 1910–19 and from age 45 for women born in 1920–29, this coefficient becomes negative and significant. Thus, for those two birth cohorts of females, there is a complete reversal of the gradient between education and smoking as individuals age and as the health related information becomes available. For females born after 1929, all coefficients are negative and significant. For females, looking vertically for the same birth cohort and abstracting from smoking at age 17, the older the individuals, the stronger the negative effect of education on smoking tends to be. The results of Tables 1 and 2 suggest that comparing smoking behaviors at ages 17 and 25 like Farrell and Fuchs 1982 misses the dynamics of smoking cessation in adult ages and that there are substantial differences in quitting behavior by edu- cation level. In the cross-sectional analysis, the negative association between schooling and smoking among females begins to appear around the time that evidence of a causal link between smoking and lung cancer became widely known. This is consistent with the hypothesis that the more educated process information more effectively to produce better health. This suggestion, however, is not true for males as college education is negatively associated with smoking behavior for all birth cohorts and at all ages. de Walque 701 Table 4 The effect of college education on smoking behavior at different ages. Panel with fixed effects, linear models. Females. Dependent variable: smoked at age 17 and smoked at ages 25 to 60 1 2 3 4 5 6 7 Birth cohort 1910–19 1920–29 1930–39 19401–49 1950–59 1960–69 1970–79 At age 25 College 0.025 0.046 0.01 0.004 ⳮ 0.032 ⳮ0.038 ⳮ0.031 [0.0104] [0.0098] [0.0085] [0.0061] [0.0047] [0.0048] [0.0099] Observations 32,010 42,282 40,304 54,630 70,600 50,240 11,290 At age 30 College 0.023 0.039 ⳮ 0.011 ⳮ 0.016 ⳮ0.048 ⳮ0.051 [0.0110] [0.0102] [0.0088] [0.0063] [0.0050] [0.0063] Observations 32,010 42,282 40,304 54,358 61,634 33,158 At age 35 College 0.015 0.025 ⳮ 0.031 ⳮ0.036 ⳮ0.053 0.058 [0.0159] [0.0102] [0.0089] [0.0066] [0.0058] [0.0109] Observations 32,010 42,282 40,304 49,450 47,166 13,484 At age 40 College 0.007 0.017 ⳮ 0.043 ⳮ0.051 ⳮ0.057 [0.0112] [0.0103] [0.0090] [0.0069] [0.0077] Observations 32,010 42,282 40,098 42,714 29,334 At age 45 College ⳮ 0.007 0.008 ⳮ 0.056 ⳮ0.061 ⳮ0.065 [0.0110] [0.0103] [0.0093] [0.0081] [0.0126] Observations 32,010 42,282 36,544 32,860 10,876 At age 50 College ⳮ 0.011 0.006 ⳮ 0.057 ⳮ0.065 [0.0110] [0.0102] [0.0096] [0.0106] Observations 32,010 42,110 31,636 21,018 At age 55 College ⳮ 0.016 ⳮ 0.0005 ⳮ0.055 ⳮ0.079 [0.0107] [0.0104] [0.0110] [0.0190] Observations 32,010 38,588 25,026 7,646 continued 702 The Journal of Human Resources Table 4 continued Dependent variable: smoked at age 17 and smoked at ages 25 to 60 1 2 3 4 5 6 7 Birth cohort 1910–19 1920–29 1930–39 19401–49 1950–59 1960–69 1970–79 At age 60 College ⳮ 0.024 ⳮ 0.008 ⳮ 0.047 [0.0105] [0.0104] [0.0137] Observations 31,826 33,538 16,304 Average age at smoking initiation for smokers College 21.62 20.79 19.58 19.42 18.8 18.01 17.52 Not college 22.82 21.25 19.78 18.91 17.93 17.09 16.77 Analysis from smoking histories from the 1978, 1979, 1980, 1987, 1988, 1992, 1995, 1997, 1998, 1999, and 2000 National Health Interview Surveys for individuals age 25 and older at the time of the survey. Smoking histories are reconstructed using the age at smoking initiation and cessation. See also Note 5. Panel linear regressions with individual fixed effects: the baseline smoking behavior is always taken at age 17. College always takes the value 0 at age 17. At ages 25 and older, it takes the value 1 for college graduates and the value 0 otherwise. Age is controlled for. Robust and clustered standard errors in square brackets. , , denote statistical significance at the 1 percent, 5 percent, and 10 percent confidence levels, respectively.

IV. A panel analysis of smoking and education