I am trying to prepare a panel dataset based on 4 different rounds of the NSSO enterprise survey datasets. I have appended the 4 different datasets having exactly the same variables in the same order using STATA. Since the data provided by the NSSO is based on sample survey wherein the same sample may not have been surveyed the next year and the sample size also varies from one year to the other. Therefore I want to make a repeated cross-section data using the NIC codes given against each sample enterprise given for each of the 4 years. Now I generated a new variable in the appended dataset called 'nic' which is intended to act as the panel variable using the following command:
egen nic=group(NIC)
When I apply the following command to set the data as panel using the panel variable 'nic', I get an error message:
xtset nic Year, yearly
The error message says: "repeated time values within panel
r(451)".
Kindly help.
Youncould consider computing within-person synthesis on some variables of interest (arith mean, harmonic mean, etc).
Hope this helps
Matt
I don't use Stata and don't have a good sense of what you are doing. However, it sounds as if you may be trying to use NIC as a unique identifier when it is not. You may have multiple enterprises sharing the same NIC. If so, you may need to first aggregate the statistics to create a single value per NIC per year.
Thanks Matthew and Bradford. Your suggestion helped me prepare the panel dataset at the 'nic' aggregate. I can now use the data as a panel dataset. I would like to ask two more questions, (i) while aggregating the statistics to get a single value per nic per year shall i compute arithmetic mean or sum? (ii) is there any way I can get the categorical variables in the panel dataset thus prepared? I mean is it possible to aggregate categorical variables to create single statistics per nic per year? Thanks in advance !
Regarding whether to calculate a mean or sum, that depends on what analysis you plan to conduct; if ultimately, you want to work with sums, then you should calculate the sum, while if you want to work with means, then you should calculate the mean. You might calculate both for different purposes. Aggregating categorical variables is more difficult. Possibly you could create a scale, depending on your data. Otherwise, I probably would pick the median. Again, it depends on what you plan to do with the data. It might make sense to calculate multiple values, possibly also using the minimum and maximum values to help set up a range.
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