![]() To convert imported dates to be stored as a date type in Stata, the functions date() and mdy() will convert non-date variables to date-formatted variables. starttime and endtime are formatted as datetimes ( %tc) and submissiondate is formatted as a date ( %td)). The Surve圜TO datetime metadata ( starttime endtime submissiondate) are already stored as date variables. ![]() For example, you could count the number of days between a survey start date and submission date, or the number of minutes between the survey was started and completed. It’s advantageous to convert these variables to a proper date format, as it allows for various logical and mathematical calculations. Survey CTO defaults to storing date variables as strings when importing them to Stata. For more information see h datetime translation. These formats are numeric, but once they are stored as a date in Stata several special Stata functions can be applied to them to help with calculations that relate to dates and time. It is important to know that dates can also have a time component (datetimes), and are then stored as the number of milliseconds since January 1, 1960. Stata stores dates as a numeric variable that captures either the number of days, months, quarters, or years since January 1, 1960. Dates in Stataĭates are especially complex to work with in Stata. In short, it’s important to match the displayed format to the content, especially for outputs, so that content can be interpretable by humans. For details on the corresponding formats for each variable type and how to format variables, type help format. This is can be used to format numeric variables to display with commas or a specific number of decimal points. To convert strings to labeled numeric formats and vice versa see the encode and decode (or sencode and sdecode user-written commands).Ī variable’s format controls how the data is displayed. The command tostring changes a numeric variable into a string variable. The command destring turns a variable from a string into a numeric (must contain all nonnumeric characters). Useful commands to go between string and numeric variables are destring and tostring. See help data_types for more information about variable types. Variables are stored as string if they have any nonnumeric character in them (this includes commas and periods if they are imported as such). String variables storage types are identified by their character length ( str4 has 4 characters, str7 has 7 characters, etc.,). Numerical and string formats can be changed using the recast command, or by specifying a storage format using the generate command. More details on how numerical formats may affect datasets is available in this guide article. Float and double are the two that can hold non-integer numbers (decimals) and are the most common. Numeric variables are stored as byte, int, long, float or double. Variable formats affect how Stata displays values of variables to the user and are loosely related to the storage type – a string cannot be displayed with significant digits for example. Storage formats such string or numeric are the variable’s type, different from its format. Labeling categorical variables is preferred and should be treated as a part of data management. ![]() Only text or IDs should ever be stored as a string variables. As a rule of thumb in Stata, ordinal and categorical variable should be stored as numeric variables with labeled values. This is also beneficial for storage size of variables. For tasks in analysis such as regression, Stata requires categorical variables to be stored as numeric variables, not string variables. Variables are stored in two broad categories: string (text) or numeric. Some data types such as dates have specific metadata attached – Januwas a Friday – that relate to storage type. This information could be how many digits of precision are required or if the variable is just 0 or 1s. This storage type determines if the software treats a variable as text or a number, and how much information is stored in each variable. Statistical software requires a storage type to determine how and what data to store about each variable or value.
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