***** Identify patients with repated death events.īysort id site (month death): gen byte repeat_deaths = sum(death=1) Since Death = 1, we can sum up the total Deaths a patient experiences and drop those values that are greater than 1-because a patient can only die once. We can do this using the bysort command and summing the values of Death. This is a handy way to make sure that your ordering involves multiple variables, but Stata will only perform the command on the first set of variables.įirst, we want to make sure we eliminate the repeated deaths from Patient 8. Stata orders the data according to varlist1 and varlist2, but the stata_cmd only acts upon the values in varlist1. The bysort command has the following syntax: bysort varlist1 (varlist2): stata_cmd Removing the patient will result in a loss of information for Site B, but keeping the patient complicates the panel data when we convert from wide to long format. There are two ways to approach this: (1) remove the patient from Site B or (2) keep the patient by distinguishing it at each sight. The highlighted boxes indicate a patient was observed at two different sites. For instance, in Month 1, there were 5 observations. For each month, there are different numbers of observations. In this example, we have a data set with time (months) in the column and patients in the rows (this is called a wide format data set).
#Sort stata code#
You can download the sample data and Stata code at the following links: However, when it comes to panel data where you may have to distinguish a patient located at two different sites or a patient with multiple events (e.g., deaths), it’s important to organize the data properly.
#Sort stata series#
For example, sorting by the time for time series analysis requires you to use the sort or bysort command to ensure that the panel is ordered correctly. The -by varlist:- prefix also requires the observations to be sorted according to the varlist.Sorting information in panel data is crucial for time series analysis. For example, to sort the countries by their geographical region ( regn) in alphabetical order and by GDP per capita ( gdppc), from highest to lowest:
#Sort stata plus#
Gsort varname varname varname …Ī plus sign (+) before the varname instructs Stata to order the observations in ascending order, while a minus sign (-) implies descending order of observations.
gsort-, on the other hand, can sort the observations in either ascending or descending order. If there are more than 2 variables, then the observations will be sorted by the first variable first, then the second variable second, and so on. Then, for observations with common var1, Stata will sort them according to var2. If there are 2 variables, var1 and var2, after sort, Stata will sort the observations according to var1 first. If varlist is only one variable, then Stata will sort the observations in ascending order based on that variable. The -sort- command put the observations in ascending order based on a specific variable or a set of variables. These two put the observations in a certain order. If the observations were in arbitrary order, then you wouldn’t know which ones were dropped or kept, would you? This is when -sort- and -gsort- come in handy. Keep in 30/l / Keeps the observations from line 30 to the last line, denoted by small letter l */ For example,ĭrop in 1/100 /* Drops the observations from line 1 to line 100 / The most obvious case is when you are using the qualifier -in- to specify a subset in your data. Is it necessary to put observations in a certain order? In a number of cases, yes.
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