In this section we discuss how to read raw data files. Statistical software spss stata easy to start, limited capability. The word real is sometimes used in place of numeric. 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.
Stata has five different types of numeric variable. 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. When stata does this, the number will look right when you browse, but attempts to run commands will turn up zero observations. 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. 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. Adding a value label to a variable in stata is a twostep process. Type \help import stata documentation is extensive and outstanding. Apr 30, 20 lets say your date of birth variable is called dob. Why am i losing precision with large whole numbers such as.
How to convert abstract value into number in stata. Nov 05, 2010 for a very long time i have used the string function substr to split all sorts of codes into components. Numeric data are sometimes imported into variables of type character and it may be desirable to convert these to variables of type numeric. 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. Variables being numeric or string is in the first instance a matter of variable type or storage type. Numbers are stored as byte, int, long, float, or double, with the default being float. Note that it is not possible to directly change the type of a variable. Typically, we think of quantitative data as numbers. Lets say your date of birth variable is called dob. Stata s capabilities include data management, statistical analysis, graphics, simulations, regression, and custom programming. In this section well take a look at two stata data sets and see how theyre put together. In this case, you want to convert the actual variable, not the format type see here. Stata is a complete, integrated statistical software package that provides everything you need for data science. The following document provides an example of how to create.
By using the appropriate variable types, you ensure that your program runs as efficiently as possible. The storage type for numeric variables can be float or byte. 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. Moreover, the format can influence the output of statistical procedures.
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. Stata takes float as the default storage type for its variables. For example, suppose a numeric variable gnp has a value of 12345678. Numbers can be stored in one of five variable types. This means that stata will not round a number stored as a float. For example, float variable type data will be stored with a 7digit level of accuracy. Issue the command describe abreviated d and look at the output. The way you can tell from describe output is to look in the storage type column. How to redetermine column type in stata stack overflow. The actual storage type and display format you can get running describe. Most directly, describe will show string variables as having some storage type for example. How a variable appears when you look at the data with browse or edit is defined by the variables format. Change missing values to numeric values and vice versa 482. Converting variable types from character to numeric.
Note that stata reports the names of each variable as well as the storage type. Mgmt 469 getting your data ready for analysis with. Each element of data is said to be either type numeric or type string. Data entered in stata can be classified either as numeric or string type.
For information about the software, type help within stata. If you send a stata dataset to a stata 7 user, be sure to use the saveold command. Why am i losing precision with large whole numbers such. In stata format means display format, which is secondary.
The module is made available under terms of the gpl v3. If you have a large data set, you may need to think about the storage space that your data set occupies. The first line of syntax reads in the dataset shown above. Convert dta file to exceldownload free software programs online. One particular thing to be aware of after insheet is that sometimes for various quirky reasons stata will mistakenly read numeric variables as strings. Stata module to recast variables from double to float storage type, statistical software components s444904, boston college department of economics.
All homeworks and examples will use data in stata format extension. 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 ships with a number of small datasets, type sysuse dir to get a list. In stata, how do i add a value label to a numeric variable. Dec 17, 2015 in reality, however, date variables are stored in string or numeric formats, which are not directly interpretable by stata.
How can i quickly convert many string variables to numeric. An example of when one might need to do this is if they needed to append. The frontier command in stata obtains its starting values using method of moments. Some common ones are text, numeric, multimedia, models, audio, code, software, discipline specific i. In contrast, large integers and floatingpoint values 123,000,000, 3. 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. We always have to put quotes around a string in stata so stata knows what we are talking about. If we use the describe command, we can see that stata stored this value with the type float. This article is part of the stata for students series. In stata, how do i display numeric values with commas inserted. The second step is to associate a specific mapping with a particular variable using the. 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. Here we use the generate command to create a new variable representing population younger than 18 years.
Since the default storage type is double, specifying byte saves 78s of the space. I have a problem with the numeric storage type of a variable. To get around the problem i needed to specify the starting values myself, which were obtained from a linear regression. If you are new to stata we strongly recommend reading all the articles in the stata basics section. How to convert categorical string variables to labeled numeric variables.
So technically, the source right now is string and the destination is numeric18,2. 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. Stata stores numeric missing values as the largest 27 numbers allowed by the particular storage type. Often when importing data, stata can mistake a numeric variable for a string variable. Specifying the data type and format in ncss youtube.
Stata is reading in my variables as string instead of numeric. 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. Associated with each type of data is its storage type i. The great divide among data types in stata is between numeric and. The following document provides an example of how to.
The second column of this list should display the storage type of all your variables. 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. File formats should be chosen to ensure sharing, longterm access and preservation of your data. 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. 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. How can i quickly convert many string variables to numeric variables. The variables may contain numeric values, but if they are defined as type. It is only possible to write the variable to a new variable containing the same data, although with a different type. There may be times that you receive a file that has many or all of the variables defined as strings, that is, character variables. The stata website is also a repository for datasets used in the stata manuals and in a number of statistical books. Convert dta file to exceldownload free software programs. In case you should try to hand in a paper to your professor in which you report this mean country value.
Additionally, a decimal value can contain a decimal point. Whether or not stata will do what you want depends on the circumstances. 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. 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. To ensure that old programs and dofiles continue to work properly, when. For a very long time i have used the string function substr to split all sorts of codes into components. Below, we use functions for translating dates stored in string and numeric formats into a stata date format.
If an expression includes a missing value at any point, the result is missing. In stata, how do i display numeric values with commas. But this it not the whole story, in at least two ways. The suggested citation for this software is statacorp. With numeric variables, you can perform any computations, meaningful or not. First, if you sort on a variable that has missing values, the missing values will be placed last, and the sort order of. In reality, however, date variables are stored in string or numeric formats, which are not directly interpretable by stata. 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. This post demonstrates how to create new variables, recode existing variables and label variables and values of variables. 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. Statistical packages with decimal storage type statalist. Changing a numeric to a string variable in stata stack. Storing numeric variables efficiently sas institute. Java how to design login and register form in java.
To insert commas into the numeric value, use this command. Stata is a complete, integrated software package that provides all your data science needsdata manipulation, visualization, statistics, and reproducible reporting. Some users of excel or similar programs get in the habit of putting several lines of. For a full list, type help functions well talk about learning from the help files in learning more. Statas data management features give you complete control. Similarly, byte, int, and long are usually used to hold integers. What youre looking for is a numeric storage type anything other than str and a date display format starts with %t, ideally %td. A program that uses more memory than is physically available will swap to disk. 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. C provides several different types of numeric variables. But once i use the command egen midmaxpid it generates automatically a variable stored as float and so the last digits result changed. For details about converting dates from other software, see using dates and times from other software. In this example, a list of numeric variables is just as useful as a list of string variables.
The variables may contain numeric values, but if they are defined as type string. This module should be installed from within stata by typing ssc install doubletofloat. The initial values might have produced negative infinity for the log likelihood. Typing describe aa will tell you what the storage type is, and typing. There are ways to save space when you store numeric variables in sas data sets. With this twostep process, you can associate one particular mapping. Stata 8 adds capacity to define more than one value for each variable to be missing. The data sets shown in this section are very small, but data sets are often very large. You can access the pdf documentation by clicking on the blue text for example, d import or by using the menu. You can tell how much memory your stata job is taking with the stata. 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. Creating an age variable from a date of brith variable. I am interested to know does any established statistical package currently support numeric data in largerthandouble formats, and decimal in particular.
Helps reduce storage and operations to read from and write to data set. Here, numeric variables can be changed to a different numeric type, and string variables to a different string type i. On april 23, 2014, statalist moved from an email list to a forum, based at. The difference has to do with how stata organizes its memory space and need not concern you. 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. Stata is a generalpurpose statistical software package created in 1985 by statacorp. Most of its users work in research, especially in the fields of economics, sociology, political science, biomedicine, and epidemiology. The table below shows the minimum and maximum values for each storage type. 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.
1271 1552 1036 706 498 571 658 77 788 1566 741 1264 153 1155 419 751 905 550 398 1571 691 1474 701 416 473 894 160 780 418 180 1314 1257 975 334 1043 683 650 1189 613 1300 1365 432 855