I am looking at a particular subset if IHIS data from 2001 to 2013. The “mod10fwk” and “vig10fwk” are supposed to represent number of times per week engaging in moderate and vigorous exercise, respectively. I have found no codebook for this variable besides to say that it is a 2-digit numeric variable.
First of all, I assume that values 94-99 are different types of “Unknown”, but I have another issue. In my data, for both of these two variables, there are 20,457 instances of 0. Zero would naturally mean that a person does not normally engage in any exercise at all, but I find it hard to believe that not a single person engages in moderate exercise but not vigorous exercise. This has lead me to believe that 0 might be code for “NIU”. Does anyone know if this is the case? And if it is, would that mean that for every other value of the variable, I need to subtract 1 to obtain the actual number of times exercised per week?
Any help is appreciated.