Stata module to identify variables with problematic missing. Title encode encode string into numeric and vice versa descriptionquick startmenusyntax options for encodeoptions for decoderemarks and examplesreferences also see description encode creates a new variable named newvar based on the string variable varname, creating, adding. The examples above all work regardless of whether the variables of interest i. When all of the variables you wish to check for missing values are numeric we can use a program called misschk to simplify the steps of examining the missing data in our dataset. As before,s may be a literal string or the name of a string variable, but is most commonly the latter. A string variable shows up in red in the data editor. The program can be installed by typing the following from the stata. In stata this is often true because stata treats stringencoded variables as missing and will not use them in analyses.
One or more spaces, despite usually conveying nothing to people, do not qualify as missing so far as stata is concerned. Matrices cannot contain missing entries in versions of stata before 8. How to replace a string variable with a missing numeric. Stata version 9 up is required but see below for a note for any people. In stata, type search dropmiss and install from the sj 84 files. This module should be installed from within stata by typing ssc install fmiss. For example, we can have missing values because of nonresponse or missing values because of invalid data entry. Its evidently a numeric variable, but you are seeing the value labels.
In stata, if your variable is numeric and you are missing data, you will see. The nmissing and npresent commands were written by nicholas j. Replacing string variables to missing 26 mar 2017, 11. If you recorded the missing values for a string variable using some kind of nonblank indicator for example, 999 or 999 and have already defined that user missing value in the variable view window, automatic recode will preserve the missing designation, but will still convert the category code to be in the range of the other categories. The first table lists the variables, their storage type type, the number of observations obs, the number of missing values mv, and the variable label if the variables has one. You can only define missing values for string variables whose length is eight or less what spss calls short string variables. I would like to delete cases if they have missing values in any variables in my dataset. The missing value could be represented by the string. The first case most often occurs when importing data from another source. Otherwise, you can use encode to convert string data into a numeric variable or decode to convert numeric variables to strings. With string variables, stata has only one definition of missing, namely that a string is empty, and contains precisely no characters. How can i see the number of missing values and patterns of missing. How can i count how many cases are missing in a string. All these columns will import as string values when they should be numeric, because of the missing values, so you wont be able to make any calculations without fixing the data.
The module identifies missing value in numerical and string variable. It returns a new dataset containing a string variable listing the terms and a numeric variable with the corresponding frequencies. As in encode, you can and should create a new variable using the gen. To indicate a missing value in a string variable, you need to use the missing values command and assign a value to missing cases. A string can contain multiple parts of information. Stata for complete beginners 100% free to download exercises and course files access. Stata module to identify variables with problematic. Click the variable view tab at the bottom of the data editor window. Stata faq how do i specify types of missing values. Dropping variables or observations with missing values help dropmiss if installed. This tutorial uses fillmissing program which can be downloaded by. The second table contains the information on the pattern of missing values. Like other statistical packages, stata distinguishes missing values.
The difference between using numeric and string values is in the number of allowable elements in the list number of countries in our example. Delete missing dear stata users, i have a question about deleting missing data. The fastest way to convert string variables into numeric ones is with the alter type command. If you recorded the missing values for a string variable using some kind of nonblank indicator for example, 999 or 999 and have already defined that usermissing value in the variable view window, automatic recode will preserve the missing designation, but will still convert the category code to be in the range of the other categories. In stata this is often true because stata treats string encoded variables as missing and will not use them in analyses. Any string in var that does not meet the conditions of rules is set to missing in created numeric variables and copied from var in created string variables. Cox and you can download them using search nmissing. Download these data you will need to unzipextract to use these data files. However, anticipating that this may be problematic, stata offers various commands to change string variables into categorical variables and vice versa. Missing values for string variables are handled similarly to the missing values for numeric variables. In fact, this finds string variables that are all missing as well. Converting an spss string variable into a numeric one is simple. You claimed that missing values were represented by. Listing nonmissing string variables in stata stack overflow.
As example, suppose we have the variables var1, var2, and var3. In the cchs dataset, many variables have missing values coded as. However, unlike numeric variables, empty fields in string variables are not designated as system missing. You can only define missing values for string variables whose length is eight or. Variables may either be recoded into numeric variables or into string variables. A string variable with missings would lead to type mismatch r109. Value labels will be defined for numeric variables. The variable names correspond to the column names of matrix.
From string to stata format this blog post discusses the conversion of text publication quality regression tables with asdoc in stata video example creating publicationquality tables in stata with asdoc is as simple as adding asdoc to stata. Reshape data in stata an easy to understand tutorial. For the case of numerical variables, also statacoded missing values e. Here, and indeed elsewhere, it helps to think of numeric missing as arbitrarily large. How can i quickly convert many string variables to numeric. Since a main issue of missing values is that it might introduce a sample selection problem, fmiss offers a very simple and purely introductive way to detect such problems.
Apr, 2019 it returns a new dataset containing a string variable listing the terms and a numeric variable with the corresponding frequencies. Spss how to convert string variables into numeric ones. Posted on 5 october 2010 by mitch abdon to concatenate is to join the characters of 2 or more variables from end to end. This value can be one or more blanks, or a numeric code such as 9999. The term blank is perhaps unclear here and thus better avoided. Tab autocompletes variable name after typing part at command prompt ctrl 9 open a new.
With a force option, datasets containing numeric variables may also be transposed. Reed college stata help changing string variables to. Stata is a good tool for cleaning and manipulating data, regardless of the. But stata records missing values as a single period.
The default download settings indicate missing values with two periods, like so. These commands rely on value labels, which are described below. However, unlike numeric variables, empty fields in string variables are not designated as systemmissing. Recode values 99 and 98 on the variable, hrs1 as missing. Different variables have different amounts of missing data and hence, changing. When i add the variable to the dataset, stata recognizes it as a string variable. You can call it whatever you want, but the variable name. For numeric values, 254 elements are allowed and for string values, only 9. Stata for econ capstone stata research guides at bates.
Recode the marital variable into a string variable and then back into a numeric variable. All these columns will import as string values when they should be numeric, because of the missing values, so you wont be able. You can download mdesc from within stata by typing search mdesc see how can i. In stata, this can be done by using either gen or egen. Create a new variable that associates each individual with the average number of hours worked among individuals with matching educational degrees see the last by example for inspiration. Can i quickly see how many missing values a variable has. The destring command allows you to convert data saved in the string format.
If you are working with string variables, the data will appear as blank. How to replace a string variable with a missing numeric value 17 oct 2018, 10. Missing values for string variables are denoted by empty string. Stata module to generate an index of terms from string variable, statistical software components s457993, boston college department of economics, revised. From this, we see all of the variables have 200 nonmissing observations, except for science that has 195 nonmissing observations. The variable does not contain nonnumeric characters. Even so, because the variable is defined as str2, stata cannot perform any kind of numerical analysis of the variable science.
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