Participants who responded “0” to the alcohol frequency question were not asked the alcohol quantity question, and were thus coded as 0 for alcohol quantity. Participants who selected I choose not to answer or Don't know to either the frequency or quantity question were coded as missing. The “grams of ethanol consumed” alcohol use variable was calculated by multiplying the product of frequency and quantity by 14 (the standard alcoholic drink contains 14 grams of ethanol per serving; i.e., Frequency × Quantity × 14).
