Q. Deduplicate PERMNO or any field in CRSP stock price csv dataset

If your dataset has less than 1,000,000 rows, you can open it in Excel 2007 or higher.

Here are the steps:

1. Sort the PERMNO field or the field you want to deduplicate and select the column
2. From the Menu bar, Data-> Filter-> Advanced Filter
3. In the Advanced Filter Dialog Box, check the "Filter the list, in-place" button, and check the "Unique records only" checkbox, then OK.

Stata can handle larger datasets.

Here are the steps to deduplicate PERMNO:

1. Assume you save the .csv file in H: drive.
2. cd H:
3. insheet using mydata.csv
4. sort permno
5. duplicates drop permno, force
6. outsheet using deduplicatedpermno.csv, c

Where deduplicatedpermno.csv is the dataset with unique PERMNOs.