Stata / Loops 删除 15,000 个观测值中的每 9-15 个观测值

Question

I am trying to create a loop that deletes every 9th-15th observations out of dataset containing around 15,000 observations. What would be the syntax?

Answer 1

In general you should not loop over observations as there is almost definitely a more efficient and elegant solution, as Nick noted above with the drop if missing(turnout) solution. However, I gather you are a new Stata user so I will run through a hypothetical. Suppose that you in fact did want to drop observations within a certain range rather than based on a secondary variable like turnout . The general strategy could be as follows:

1. Group observations in groups of 15 (which I think you have here with the id column). In the solution below I will assume you do not have this column.
2. Within each group, drop the observations in the 9th-15th places.

// Group observations
gen group = ceil(_n/15)
// Within each group, drop in the 9-15 locations 
by group: drop if inrange(_n,9,15)

Answer 2

drop if mod(_n, 9) == 0 

will drop observations 9, 18, 27, and so forth. The same principle applies to any other positive integer.