Changes

Individuals who either never smoked, or on whom we have no data (e.g., someone was a former smoker but former smoking was never assessed) will be excluded from analysis.  Only cigarettes will be included in the estimate.  If preferable, repeated measures designs (longitudinal data) can use all assessments by scaling and correcting for covariates within waves of assessment, then averaging across assessments.

Individuals who either never smoked, or on whom we have no data (e.g., someone was a former smoker but former smoking was never assessed) will be excluded from analysis.  Only cigarettes will be included in the estimate.  If preferable, repeated measures designs (longitudinal data) can use all assessments by scaling and correcting for covariates within waves of assessment, then averaging across assessments.

There was some cross-study variability on this measure. Some studies specified avg smoking during a specific window, such as the last 12 months; most made no such specification. One study allowed respondents to report packs.

For studies that collect a quantitative measure of CPD, where the respondent is free to provide any integer (e.g., 13 CPD), '''we will bin responses into the following bins: 1-10, 11-20, 21-30, 30+.''' If some study collected binned responses from the outset, and those bins happen to differ from ours (e.g., 1-5, 6-15, etc.), then we will simply use whatever bins the study has collected. Please contact Scott if your study does something completely different.

=== (2) Smoking Initiation ===

=== (2) Smoking Initiation ===

=== Ordinal versus Quantitative Phenotypes ===

=== Ordinal versus Quantitative Phenotypes ===

For studies with ordinal measures, such as questions that force the respondent to report ranges (e.g., 0, 1-10, 11-20, 21-30 cigarettes per day), please use midpoint of the range. These midpoints should then be treated as if they were quantitative variables in all further analysis.

For studies with ordinal measures, such as questions that force the respondent to report ranges (e.g., 1-5, 6-10, 21-30 cigarettes per day), please use midpoint of the range. These midpoints should then be treated as if they were quantitative variables in all further analysis.

== Covariates ==

== Covariates ==