TRANTIME Specific Variable Codes

#1

I am working with data comparing commuting times from the 1980, 1990, and 2000 decennial censuses and have a question regarding the large number accumulated at ‘0’.

In the data description for TRANTIME it lists a variable specific code such that ‘000 = N/A’.

After downloading the data as a .dat file I noticed all values have leading zeros and I cannot differentiate between those with a true zero commute time and those who should be treated as ‘N/A’.

Additionally, the format file for Stata imports the TRANTIME variable as an integer which sets all values to simply ‘0’. This is also the case when downloading data as a Stata formatted dta file.

Is it possible using the data as is, or perhaps an additional variable, that can be used to differentiate between the two groups?

Thanks for any help you can provide.

What does N/A code mean for tranwork variable
#2

As the universe statement of the TRANTIME variable suggests, respondents need to be (a) 16 years old or older and (b) working outside of their home last week to be eligible for this question. That is those who have a value of 0 for TRANTIME are either: not included in the migration/place of work/travel time sample, under the age of 16, not at work, or worked at home. So, if you keep only those who are over the age of 16, employed (EMPSTAT==1), and who work outside of the home (TRANWORK==10 through 50), then you should not see any zeros for TRANTIME in the data. Note that for the 1980 sample, you will need to use the MIGSAMP variable to identify people who are part of the migration sample.