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Introduction to Stata 8 - (GRIPS

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In commands that have a dependent variable, it is the first in the varlist:<br />

oneway bmi sex<br />

bmi is the dependent variable<br />

regression bmi sex age bmi is the dependent variable<br />

scatter weight height scatterplot, weight is y-axis<br />

tabulate expos case The first variable defines the rows<br />

Conditional commands. The if qualifier [U] 14.1.3.<br />

The opera<strong>to</strong>rs used in conditions are defined in section 10.1. Here are a few examples:<br />

summarize age if sex==1<br />

statistics for males only<br />

list id age if age < 35 list only if age < 35<br />

replace npreg=. if sex==1 set npreg <strong>to</strong> missing for males<br />

Numeric ranges. [U] 14.1.4<br />

Numeric ranges are marked by a slash:<br />

recode age (1/9.999=1)(10/19.999=2) , generate(agegrp)<br />

Number lists. The in qualifier [U] 14.1.8<br />

A number list (numlist) is a list of numbers; there are some shorthand possibilities:<br />

1(3)11 means 1 4 7 10<br />

1(1)4 4.5(0.5)6 means 1 2 3 4 4.5 5 5.5 6<br />

4 3 2 7(-1)1 means 4 3 2 7 6 5 4 3 2 1 (Danish CPR number test)<br />

1/5 means 1 2 3 4 5<br />

4/2 7/1 means 4 3 2 7 6 5 4 3 2 1 (Danish CPR number test)<br />

Example:<br />

list sex age weight in 1/10 // observations 1 <strong>to</strong> 10<br />

Weighting observations [U] 14.1.6, [U] 23.13<br />

A typical use is <strong>to</strong> 'multiply' observations when the input is tabular:<br />

Cases Controls<br />

Exposed 21 30<br />

Unexposed 23 100<br />

Total 44 130<br />

. input expos case pop // see section 8<br />

1 1 21<br />

1 0 30<br />

0 1 23<br />

0 0 100<br />

. end<br />

. tabulate expos case [fweight=pop] , chi2 // see section 11.1<br />

. cc expos case [fweight=pop] // see section 11.1<br />

Immediate commands (section 15.5) use tabular input directly.<br />

14

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