The way you can tell from describe output is to look in the storage type column. Stata has a large library of functions you can use in gen and replace expressions, far too many for us to cover them all though well introduce some as we go. If we use the describe command, we can see that stata stored this value with the type float. Cs numeric variables fall into the following two main categories. For instance, stata will compute the mean of the variable representing the country respondents come from, should you so desire. Numeric precision in sas software how sas stores numeric values to store numbers of large magnitude and to perform computations that require many digits of precision to the right of the decimal point, sas stores all numeric values using floatingpoint, or real binary, representation. Mgmt 469 getting your data ready for analysis with. In reality, however, date variables are stored in string or numeric formats, which are not directly interpretable by stata.
Each element of data is said to be either type numeric or type string. In this section well take a look at two stata data sets and see how theyre put together. Stata stores numeric missing values as the largest 27 numbers allowed by the particular storage type. The following document provides an example of how to create. Numeric data are sometimes imported into variables of type character and it may be desirable to convert these to variables of type numeric. Often when importing data, stata can mistake a numeric variable for a string variable. An example of when one might need to do this is if they needed to append. Below, we use functions for translating dates stored in string and numeric formats into a stata date format. Lets say your date of birth variable is called dob. You need different types of variables because different numeric values have varying memory storage requirements and differ in the ease with which certain mathematical operations can be performed on them.
Typically, we think of quantitative data as numbers. Whether or not stata will do what you want depends on the circumstances. Issue the command describe abreviated d and look at the output. Stata takes float as the default storage type for its variables. Remarks and examples closest to 0 storage type minimum maximum without being 0 bytes byte 127 100 1 1 int 32,767 32,740 1 2. Stata module to recast variables from double to float storage type, statistical software components s444904, boston college department of economics. Why am i losing precision with large whole numbers such as. The data sets shown in this section are very small, but data sets are often very large.
Type \help import stata documentation is extensive and outstanding. Defining the number of decimal values means defining the maximum number of decimal values displayed, whereas not defining the number of decimal values will make stata display as many decimal places as are present, within the limits of the overall width of. To get around the problem i needed to specify the starting values myself, which were obtained from a linear regression. The storage type for numeric variables can be float or byte. The table below shows the minimum and maximum values for each storage type. Some common ones are text, numeric, multimedia, models, audio, code, software, discipline specific i. I have a problem with the numeric storage type of a variable. What youre looking for is a numeric storage type anything other than str and a date display format starts with %t, ideally %td. Numbers are stored as byte, int, long, float, or double, with the default being float. A program that uses more memory than is physically available will swap to disk. There may be times that you receive a file that has many or all of the variables defined as strings, that is, character variables.
For example, suppose a numeric variable gnp has a value of 12345678. Stata is a complete, integrated software package that provides all your data science needsdata manipulation, visualization, statistics, and reproducible reporting. Stata ships with a number of small datasets, type sysuse dir to get a list. If you send a stata dataset to a stata 7 user, be sure to use the saveold command. For details about converting dates from other software, see using dates and times from other software. Change missing values to numeric values and vice versa 482. Use this option when there is little or no loss of information as in the conversion of some variables of double type to variables of float type, etc. Stata 8 adds capacity to define more than one value for each variable to be missing.
To store numbers of large magnitude and to perform computations that require many digits of precision to the right of the decimal point, sas stores all numeric values using floatingpoint, or real binary, representation. The stata website is also a repository for datasets used in the stata manuals and in a number of statistical books. File formats should be chosen to ensure sharing, longterm access and preservation of your data. We suggest you use the data type and format editor tool to specify the data type and choose a display format for columns in your dataset. Stata is a generalpurpose statistical software package created in 1985 by statacorp. In stata format means display format, which is secondary. Most stata commands save results in variables so you can use them later for example, if you type help summarize, the last item in the help window is a a list of stored results another way of obtaining the list is by typing return list or ereturn list stata is always well organized, which is great for stata but sometimes. On april 23, 2014, statalist moved from an email list to a forum, based at. When stata does this, the number will look right when you browse, but attempts to run commands will turn up zero observations. The variables may contain numeric values, but if they are defined as type. Oct 23, 20 we suggest you use the data type and format editor tool to specify the data type and choose a display format for columns in your dataset. You can tell how much memory your stata job is taking with the stata.
The word real is sometimes used in place of numeric. Convert dta file to exceldownload free software programs. The first line of syntax reads in the dataset shown above. This post demonstrates how to create new variables, recode existing variables and label variables and values of variables. Changing a numeric to a string variable in stata stack. For example, float variable type data will be stored with a 7digit level of accuracy. In stata, how do i display numeric values with commas inserted. Variables being numeric or string is in the first instance a matter of variable type or storage type. Moreover, the format can influence the output of statistical procedures. Some users of excel or similar programs get in the habit of putting several lines of. The great divide among data types in stata is between numeric and.
Associated with each type of data is its storage type i. Statistical packages with decimal storage type statalist. It is only possible to write the variable to a new variable containing the same data, although with a different type. The actual storage type and display format you can get running describe. Here, numeric variables can be changed to a different numeric type, and string variables to a different string type i. In stata, how do i add a value label to a numeric variable. Java how to design login and register form in java.
The frontier command in stata obtains its starting values using method of moments. C provides several different types of numeric variables. We always have to put quotes around a string in stata so stata knows what we are talking about. Most directly, describe will show string variables as having some storage type for example. I am interested to know does any established statistical package currently support numeric data in largerthandouble formats, and decimal in particular. Apr 30, 20 lets say your date of birth variable is called dob. With this twostep process, you can associate one particular mapping. In contrast, large integers and floatingpoint values 123,000,000, 3. Data entered in stata can be classified either as numeric or string type. See, for example, quantitative file formats for preservation, a post on the digital preservation coalition blog, which indicates that the bulk of the datasets received by the irish social science.
Creating an age variable from a date of brith variable. Title data types quick reference for data types descriptionremarks and examplesalso see description this entry provides a quick reference for data types allowed by stata. Note that it is not possible to directly change the type of a variable. In stata, how do i display numeric values with commas. Typing describe aa will tell you what the storage type is, and typing. Mar 09, 2019 numeric data are sometimes imported into variables of type character and it may be desirable to convert these to variables of type numeric.
But this it not the whole story, in at least two ways. The database i am working with echp presents a variable stored as double, since it has more then 14 digits, and i want to generate its maximum. The initial values might have produced negative infinity for the log likelihood. This module should be installed from within stata by typing ssc install doubletofloat. In this case, you want to convert the actual variable, not the format type see here. Numbers can be stored in one of five variable types. But once i use the command egen midmaxpid it generates automatically a variable stored as float and so the last digits result changed. Dec 17, 2015 in reality, however, date variables are stored in string or numeric formats, which are not directly interpretable by stata. The suggested citation for this software is statacorp. This means that stata will not round a number stored as a float. Convert dta file to exceldownload free software programs online.
I suspect you ran the first one, freaked out that this is a string variable, and then decided to convert it, even though it was not necessary since it was a numeric variable, to begin with. To insert commas into the numeric value, use this command. Adding a value label to a variable in stata is a twostep process. You can access the pdf documentation by clicking on the blue text for example, d import or by using the menu. Similarly, byte, int, and long are usually used to hold integers. The problem is that a float can only store an integer value with up to 7 digits of accuracy but our id values were 9 digits. The format of stata stystem files has changed to accommodate longer storage types. How to convert categorical string variables to labeled numeric variables. Statistical software spss stata easy to start, limited capability. One particular thing to be aware of after insheet is that sometimes for various quirky reasons stata will mistakenly read numeric variables as strings.
How a variable appears when you look at the data with browse or edit is defined by the variables format. Stata is reading in my variables as string instead of numeric. Why am i losing precision with large whole numbers such. The difference has to do with how stata organizes its memory space and need not concern you. Storing numeric variables efficiently sas institute. If you are new to stata we strongly recommend reading all the articles in the stata basics section. If an expression includes a missing value at any point, the result is missing. The following document provides an example of how to. Converting variable types from character to numeric. Specifying the data type and format in ncss youtube.
For a full list, type help functions well talk about learning from the help files in learning more. All homeworks and examples will use data in stata format extension. In case you should try to hand in a paper to your professor in which you report this mean country value. Helps reduce storage and operations to read from and write to data set.
First, if you sort on a variable that has missing values, the missing values will be placed last, and the sort order of. The module is made available under terms of the gpl v3. The variables may contain numeric values, but if they are defined as type string, there are very few things you can do to analyze the data. The second column of this list should display the storage type of all your variables. How can i quickly convert many string variables to numeric variables. If you have a large data set, you may need to think about the storage space that your data set occupies. How can i quickly convert many string variables to numeric. Most of its users work in research, especially in the fields of economics, sociology, political science, biomedicine, and epidemiology. Stata s capabilities include data management, statistical analysis, graphics, simulations, regression, and custom programming. With numeric variables, you can perform any computations, meaningful or not. One method of converting numbers stored as strings into numerical variables is to use a string function called real that translates numeric values stored as strings into numeric values stata can recognize as such. In this section we discuss how to read raw data files.
For a very long time i have used the string function substr to split all sorts of codes into components. For example, if i want to split the philippine standard geographic codes psgc into smaller geographical units, i would write the following codes see note below. To ensure that old programs and dofiles continue to work properly, when. So technically, the source right now is string and the destination is numeric18,2. This article is part of the stata for students series.
Here we use the generate command to create a new variable representing population younger than 18 years. Stata has five different types of numeric variable. Statas data management features give you complete control. For information about the software, type help within stata. How to redetermine column type in stata stack overflow. The second step is to associate a specific mapping with a particular variable using the. By using the appropriate variable types, you ensure that your program runs as efficiently as possible. There are ways to save space when you store numeric variables in sas data sets. Most of its users work in research, especially in the fields of economics, sociology, political science, biomedicine, and epidemiology statas capabilities include data management, statistical analysis, graphics, simulations, regression, and custom programming. In this example, a list of numeric variables is just as useful as a list of string variables. Nov 05, 2010 for a very long time i have used the string function substr to split all sorts of codes into components.
Stata is a complete, integrated statistical software package that provides everything you need for data science. Since the default storage type is double, specifying byte saves 78s of the space. If you want to change from numeric to string, or vice versa, that is a matter of changing storage type. Note that stata reports the names of each variable as well as the storage type. Note, however, that a comma is required before a negative number that follows another numeric expression, or the minus sign is interpreted as a subtraction operator. How to convert abstract value into number in stata. Additionally, a decimal value can contain a decimal point. Floatingpoint representation is an implementation of what is generally known as scientific notation, in which values are represented as numbers between 0 and 1 times a power. The variables may contain numeric values, but if they are defined as type string.