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How does Stata deal with missing values?
3. Summary of how missing values are handled in Stata procedures. summarize For each variable, the number of non-missing values are used. tabulation By default, missing values are excluded and percentages are based on the number of non-missing values.
Why does Stata generate missing values?
| Stata FAQ. Sometimes, a data set may have “holes” in it, that is, missing values. Some statistical procedures such as regression analysis will not work as well, or at all, on a data set with missing values. This is why the “n” often varies from analysis to analysis, even if the dataset is the same.
What is the Egen command in Stata?
The Stata command egen, which stands for extended generation, is used to create variables that require some additional function in order to be generated. Examples of these function include taking the mean, discretizing a continuous variable, and counting how many from a set of variables have missing values.
How are missing values handled in Stata command?
As a general rule, Stata commands that perform computations of any type handle missing data by omitting the row with the missing values. However, the way that missing values are omitted is not always consistent across commands, so let’s take a look at some examples.
How to replace missing values in Stata without tsset?
Without tsset: copying nonmissing values Let us first look at the case where you have not tsset your data (see, for example, [TS] tsset for an explanation), but we will assume that the data have been put in the correct sort order, say, by typing If missing values occurred singly, then they could be replaced by the previous value
What causes values to be nonmissing in Stata?
Typically, this occurs when values of some variable should be identical within blocks of observations, but, for some reason, values are explicitly nonmissing within the dataset only for certain observations, most often the first.
Is there a way to replace myVar in Stata?
. gen mycopy = myvar . replace myvar = mycopy [_n-1] if myvar >= . No replacement is being made in mycopy, so there is no cascade effect. replace just looks across at mycopy and back one observation. 4. Copying following values upwards