Those with an affirmative response in JNTINJURY were asked the follow-up question, "How many weeks or months, in the past year, did you have joint symptoms due to an injury?" Responses to this follow-up question are contained in the complementary variables JNTINJURYTP (Duration of (injury) joint symptoms: Time period) and JNTINJURYNO (Duration of (injury) joint symptoms: Number of units). For the original NHIS public use data files, the National Center for Health Statistics recoded the data included in JNTINJURYTP and JNTINJURYNO into a third variable with a single time period, JNTINJURYMO, which indicates the duration of injury-caused joint symptoms in months.