Stata Study Notes (iii): Calculation of some of the knowledge used for the standard deviation of ROA within five years

1. How to delete data for a few rows

if year2== | year2==

2. How to calculate the standard deviation for successive years

The *YEAR2 is of type int

Bys stkcd (year2): gen roa1=adjroa[_n-1]bys stkcd (year2): gen roa2=adjroa[_n-2]bys STKCD (year2): gen roa3=adjroa[_n+1]bys stkcd (year2): gen roa4=adjroa[_n+2]egen ROASD=ROWSD (roa1 roa2 adjroa roa3 roa4)

3. How to implement data import and export of Excel and Stata?

Copy and paste on the line ~

4. How do I open a CSV format file?

using " path + file name ", clear

5. How to implement grouping and averaging?

*bysort year Group is calculated in terms of years and industries, mean for averaging, Meanroa for new variable names, Egen to generate a new set of variables

bysort Year  Group:    egen meanroa=mean (ROA)

6. How do I group numbers on my data?

Egen new_id = Group (Industry)

7. Renaming variables

ren f050201b ROA

Stata Study Notes (iii): Calculation of some of the knowledge used for the standard deviation of ROA within five years