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Introduction to Stata 8 - (GRIPS

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8. Getting data in<strong>to</strong> <strong>Stata</strong> [U] 24; [GSW] 7<br />

On exchange of data with other programs, see section 15.8.<br />

Open <strong>Stata</strong> data [R] save<br />

Read an existing <strong>Stata</strong> data set from disk in<strong>to</strong> memory by:<br />

use c:\dokumenter\p1\a.dta [ , clear]<br />

If there are data in memory, use will be rejected unless you specify the clear option.<br />

You may also issue a clear command before the use command:<br />

clear<br />

If you want only observations that meet a condition:<br />

use c:\dokumenter\p1\a.dta if sex==1<br />

If you want the first 100 observations only:<br />

use c:\dokumenter\p1\a.dta in 1/100<br />

If you want <strong>to</strong> work with only a subset of variables:<br />

use age sex q1-q17 using c:\dokumenter\p1\a.dta<br />

Save <strong>Stata</strong> data [R] save<br />

Save the data in memory <strong>to</strong> a disk file by:<br />

save c:\dokumenter\p1\a.dta [ , replace]<br />

If you already have a disk file with this name, your request will be rejected unless you specify<br />

the replace option. Only use the replace option if you really want <strong>to</strong> overwrite data.<br />

Enter data with EpiData<br />

To enter data I recommend EpiData, available for free from www.epidata.dk. This easy-<strong>to</strong>use<br />

program has all the facilities needed. Further information in appendix 2.<br />

Enter data as commands or in a do-file [R] input<br />

Very small data sets. Define the variables with the input command and enter the values.<br />

Finish with end. It can be done interactively from the command line or in a do-file. See<br />

more examples in section 14.7 (Graph examples).<br />

. input case expos pop<br />

0 0 100<br />

0 1 30<br />

1 0 23<br />

1 1 21<br />

. end<br />

You may also enter data directly in <strong>Stata</strong>'s data window (not recommended; see section 2 and<br />

[GSW] 6, 9).<br />

16

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