will create five dummy variables, marst1 to marst5, each representing one of the categories of variable marstat. JavaScript must be enabled in order for you to use our website. The mean is 187.93 and the replace works when the variable already exists, and will give an error if the variable does not yet exist. To learn more, see our tips on writing great answers. Note that if a case has one or several missing missing values, "rowmean" will be computed from those variables that have valid values. 1224c There is an even shorter way to create a 0/1 coded variable; however, you should use this only in the absence of missing values (or if you take special precautions). Note, however, that missing values will be counted as zeros, and therefore this command should be used with very much caution. You may also use numbers other than 1 if cirumstances demand it. You may use pc(income), prop instead, which will yield the same values expressed as proportions (i.e., .333333, etc., in our example). three categories. CLIR Postdoctoral Fellow 0g Often, conditional transformations are used to create indicator variables, that is variables coded "1" to denote the presence of a property and "0" to denote its absence (sometimes, particularly in the context of regression models, such variables are termed "dummy variables"). For once, let me start with a general formulation of the syntax: "Expression" can be a mathematical argument. First, we make a copy of To create new variables (typically from other variables in your data set, plus some arithmetic or logical expressions), or to modify variables that already exist in your data set, Stata provides We do so by summing up the two existing variables: poplt5 (population < 5 years old) and pop5_17 (population of 5 to 17 years old). You will proceed as follows: generate pincome = income[_n+1] if sex==1 We do so by summing up the two existing variables: In the case of ties, each case will be assigned the mean rank. Suppose that we wanted to break mpg down into Ka7kE(J I am working with Stata. Memory in Stata Version 11 or Earlier As of this writing, Stata is in version 15. >> Learning, Hours & By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. we can create dummy variables using gen command and also with tabulate command with gen command in STATA mileage of the cars with respect to their origin. In this section we will use Stata commands to label and transform variables, and to create new variables that are functions of existing variables. Note that the first line might also go like this: (see section about non-mathematical functions above), which is helpful especially if you wish to adress more than two values. A number of more complex possibilities have been implemented in the "egen" command. 11012j You create a new variable in Stata using the generate command, usually abbreviated gen. You can change the value of an existing variable using But the great thing about cond is that it may be used recursively. Typically the data might sorted, first, by the couple id, and next by gender, let's say with the male partner (sex=1) coming first, followed by the female partner (sex=2). document.getElementById( "ak_js" ).setAttribute( "value", ( new Date() ).getTime() ); Department of Statistics Consulting Center, Department of Biomathematics Consulting Clinic. ), generate clerical = inrange(isco88, 400, 490). To further continue our example. Stata Basics: Create, Recode and Label Variables 1 -generate-: create variables. Here we use the -generate- command to create a new variable representing population younger than 18 years old. 2 -replace-: replace contents of existing variables. 3 Recode variables. 4 Label variables and values. Part I: How to generate your own Stata schemes Scheme files are text files that are read by Stata at the time of drawing the graph. len_ft. To do so, use the options mean(value) and or std(value). length. Note that cases with missing values in the original variable will be assigned missing values for all of the newly created dummy variables. Think, for instance, about a person who was asked to describe what happened once she had left school. New variables often use the information gathered in other variables by denoting certain combinations of values. replace pincome = income[_n-1] if sex==2. Or we might want to make loglen which is the natural log of length. (Also note that the values I have used in this example are entirely fictitious; "isco88" is actually a categorization of occupations, but I did not look it up to find out which among these actually may be termed professions. However, I updated the question to be more precise, and I suspect the solution you provided is not suitable anymore. The code I have tried, which doesn't seem to work is as follows: qui foreach v will create standardized values of the variable income. In this section we will see how to compute variables with More about "conditional" transformations will follow in the next section but one. You will have noticed that cond(income > 3000) in this example actually means > 3000 and <= 5000, as cases where income is larger than 5000 will never reach the third argument of the main clause. W. Ludwig-Mayerhofer, Stata Guide | Last update: 25 Jul 2017, Multiple Imputation: Analysis and Pooling Steps, x rounded in units of y (i.e., round(x,.1) rounds to one decimal place), returns uniformly distributed numbers between 0 and nearly 1, returns numbers that follow a standard normal distribution, returns numbers that follow a normal distribution with a mean of x and a s.d. For an existing variable, you need to use the Often, such relations may be combined; we wish to do something "if this" is the case "and if" something else is also the case. Finally, let me mention a few more complex functions (complex only inasmuch as they need a little bit more of explanation): will compute for each case the percentage of the total of income. We can use the -recode- command to recode variables as well. rev2022.11.18.43041. Here we are talking about relational operators (is something greater or smaller than, or [not] equal to something else?). 1 if at/above the median mpg for its group (foreign/domestic). replace income_combined = income_2 if income_2 < 98. This method is very simple inasmuch as it creates an indicator variable for each and every different value of the respective variable. But in addition, she has held another job in months 10 to 12 and a further job in months 13 to 16. The command I use works like this (note that the suffix [_n-1] refers to the previous row in the data set; thus ID[_n-1] is the ID in the row immediately above the row to which a command is applied): generate maxend = end if ID != ID[_n-1] 2[U] 27 Commands everyone should know Data manipulation [U] 13 Functions and expressions generate, replace [D] generate egen [D] egen rename [D] rename,[D] rename group clear [D] Then we create a new variable called pop_c and transform the original variable pop into three categories. Here are a few I found helpful. A simple case might concern the question whether a person is married (and living with her or his partner), cohabiting (living with a partner without being married), belonging to a "LAT" (living apart together) couple, or single. Variable v323r will contain the rank of each case in v323. This will store the number of missing values that occur in the variables listed in variable "nmiss". Indeed, in this special case you should use, e.g. With the help of "rowmiss" (see next item) this may be changed. Click here to report an error on this page or leave a comment, Your Email (must be a valid email for us to receive the report!). Now I want to replace the variable graduate if a condition relative to global is met, but I get an error: My code is: String variables can have a length of 1 to 244 characters; the format is "stringX" with X being replaced by the number of characters you wish to allocate to the variable. For instance. controlling order of operations. But now look at the following data. Wave functions as being square-integrable vs. normalizable, Unable to use result of a "subquery in select clause" in a "insert.. select.. on duplicate update" query. This is a very helpful video to create a new variable by using "bysort" and "egen" command together in Stata. There is an option , missing, but this will only yield a missing value in the resulting variable if all variables that enter the computation have missing values. [,=5 111j Of course, in this simple example this might be easily repaired by adding a line such as, for instance: Note that there is a simple way of creating dummy variables related to the tab command. I call such transformations "conditional" -- something is supposed to happen on the condition that something else is the case. You may "standardize" proposing a mean and standard deviation different from the usual values of 0 and 1, respectively. In this case, you will have to refer to the variable by replace in all subsequent steps. replace pincome = income[_n-1] if sex==2. egen nmiss = rowtotal(x1-x10 var15-var23). How do I produce a PDF from imagemagick with Fast Web View enabled? As outlined above, you will often want to use some maths when creating or changing variables, like adding, multiplying and so on. Is Median Absolute Percentage Error useless? A separate window with the histogram displayed will be opened. For instance, you may first define a new variable with generate and then modify it for a subset of cases (i.e. In Stata you can create new variables with If you omit this fourth argument, missing values will be coded as 3. This information can be found on our STATA FAQ page: How can I draw a random sample of my Say that variable group takes on the values 1, 2, and Lets use tabulate to check that this worked correctly. Note that on the right hand of the equals sign you do not indicate a numeric value to be assigned; all that is mentioned is a condition, namely, that a case should have values 1 or 2 in variable marstat. MG0VqfMzFS|RbvhqS>tpiB% RZDZ\kQ G4qOU,/lc"s~@+U!EPG+[0.Uj|V;]6(YsYsC/TP?qik0 +?&1Xym?@! will compute for each case the mean of variable income of the "group" defined by v3 to which the individual case belongs (e.g., mean income of household, district, country whatever v3 is standing for). This person may have held a job in the first month (denoted by "j" in the table), and in the second month she entered college ("c") where she stayed until month 24. 8 0 obj << SA23-2275-01. The egen functions max() and min() can only be used within egen calls. egen myindex = rowmean(var15 var17 var18 var20 var23). % replace married = 0 if marstat > 2 & marstat < . I updated the example to avoid misconceptions. It may also be achieved with the "short" version of generating dummy variables outlined in the previous section, the only difference being that you may use cond with other (resulting) values than 1 and 0 (e.g., you might have written gen highinc = cond(income > 5000, -17, 3000) however nonsensical this may seem.). Recode mpg into mpg3a, having This heading refers to variables that are created or modified via reference to another row in the data set. The command I use works like this (note that the suffix [_n-1] refers to the previous row in the data set; thus ID[_n-1] is the ID in the row immediately above the row to which a command is applied): generate maxend = end if ID != ID[_n-1] Rather, the variable will be indeed counted twice (or more frequently). However, it seems JavaScript is either disabled or not supported by your browser. But replace is needed not infrequently if you cannot or do not want to create a new variable in a single rush. negative values will be turned into positive ones. Still, this entry is rather lengthy. Of course, operators and other arguments may be combined, and parentheses can be used to clarify the order in which operators are supposed to work. 11012j Some of these are the following (use "help function" in Stata to learn more): generate profession = inlist(isco88, 101, 125, 170, 171, 172, 202, 310), The new variable "profession" will have a value of 1 if (extant) variable "isco88" has any of the values that now follow; otherwise, the value will be zero. This creates variable "agroup" from variable age, grouping age into 4 categories as follows: Networks, Innovative Teaching & The example I use requires some knowledge of lags (treated further below), as this is a context in which the function described here may be particularly important. leave Stata : generate : creates new variables (e.g. Let's assume that the exact answers are stored in variable income_1 and the categorized answers in income_2. Find centralized, trusted content and collaborate around the technologies you use most. The previous sentence shows, even though implicitly, that generate and replace can be combined with an if clause (just as almost any other Stata command can). The first step would be to find out, for each episode in the data, whether there is (at least) one other episode with which it overlaps. The example I use requires some knowledge of lags (treated further below), as this is a context in which the function described here may be particularly important. site, Accounts & The range from 25 to 70 is divided into four equally spaced intervals (25 to 36.25, more than 36.25 to 47.5 etc.) has an income of 500 and a second case has an income of 1000, the first case will have a value of 33.3333 in variable pcincome, etc. Here we convert Thanks for your answer. For beginners, it may be important to bear in mind that the moment a variable is generated, it exists; therefore, even a variable that has just be created via generate, in the next step has to be addressed by replace. negative values will be turned into positive ones. For beginners, it may be important to bear in mind that the moment a variable is generated, it exists; therefore, even a variable that has just be created via generate, in the next step has to be addressed by replace. First, load the data by typing the following into the Command box and clicking Enter:. if certain conditions are fulfilled). As outlined in the introductory section, often something is to be done "if" something is the case; e.g., if a variable has, or has not, or is larger than, a certain value. Several Stata users have written programs that create publication-quality tables. As will be shown in this document, almost any operation that can be applied to a data set in Stata can also be accomplished in pandas. ), generate clerical = inrange(isco88, 400, 490). :BQ`(->]kSUv`Bm_erUSUny\[%mW9*U}!Uy(/ 2^^_rr0lzu /Rgf}u5j)VmoPRB /"dxp(!1fXcK>0?`e9,Gj#e.DbCTo97$C2LN88(4YJ!s;`|A6ENVoE'u N@gN'9k3.M ]xaNk;E6:;Vr]moh(q^;l`{]tF2CEN:fJha{4NY[Z::/5Yj.#cZ/(jo /rNJpu%3I 7h+f51kpdC{f/!jeL:75"tFFS8. We can check using this below, and the recoded value mpgfd looks correct. Often, such relations may be combined; we wish to do something "if this" is the case "and if" something else is also the case. Note that if, for whatever reason, a variable is included twice (or even more frequently) in the list (as in rowmiss(x1 x2 x2 x3)) this will not result in an error. We use variables of the census.dta data come with Stata as examples. The first quartile ; The median; The third quartile ; The maximum This tutorial explains how to create and modify box plots in Stata . Here we are talking about relational operators (is something greater or smaller than, or [not] equal to something else?). This is document afrg in the Knowledge Base. 's comment is right after all! That is, the new variable gets "this" value if something is the case, or "that" value if something else is the case, or finally "yet another" value if again something else is the case. In the dialogue box that opens, choose a variable from the drop-down menu in the Data section, and press Ok. R equivalent of Stata `tabulate , generate( )` command, rslblissett.com/wp-content/uploads/2016/09/RTutorial_160930.pdf, Performant is nonsense, but performance can still matter. Thus far, you may say: So what? Here are some examples: Note that functions that refer to several variables (such as the mean, total, or statistical parameters, over a number of variables) are available with the egen command (see below ). In Stata, the functionality of commands can be enhanced by adding qualifiers like if and in, and prefixes like by and bysort. If they do not want to give an exact figure, they are asked whether their income is within a certain income bracket; this often triggers a considerable number of additional, albeit somewhat less exact, answers. Variable v323r will contain the rank of each case in v323. Count the number of features in a given map extent as dynamic text in map layout. three categories to help make this more readable. replace x = 5 if price == 4099 replace x = 5 if price == 4749 generate y = 5 if price == 4099 | A simple case might concern the question whether a person is married (and living with her or his partner), cohabiting (living with a partner without being married), belonging to a "LAT" (living apart together) couple, or single. We see that the median is 19 for the domestic (foreign==0) cars and 24.5 for the foreign (foreign==1) cars. This will store the number of missing values that occur in the variables listed in variable "nmiss". Consider the following real-life example: In surveys, respondents are often asked about their income. Note that you cannot use the expression "170/172" (meaning 170 thru 172) here. Tweet. The clause & marstat < . 0 if below the median mpg for its group (foreign/domestic) This module shows how to create and recode variables. The Stata functions max() and min() require two or more arguments and operate rowwise (across observations) if given a variable as any one of the arguments. /Length 2795 The variable length contains the length of the car in inches. Stata automatically assigns the value "1" if this condition is "true" and the value "0" if it is not. When the migration is complete, you will access your Teams at stackoverflowteams.com, and they will no longer appear in the left sidebar on stackoverflow.com. It is one of Stata's programming functions, which may however invoked in the context of everybody's work of writing do-files. Here are a few I found helpful. will create five dummy variables, marst1 to marst5, each representing one of the categories of variable marstat. Following are examples of how to create new variables in Stata using the gen (short for generate) and egen commands: Alternatively, use egen with the built-in rowtotal option: Alternatively, use egen with the built-in rowmean option: Stata also lets you take advantage of built-in functions for variable transformations. You may connect a newly created variable to the name of a value label, such as in: The value label "lflabel" may or may not already have been defined. bysort v3: egen pct30income = pctile(income), p(30). two categories, but using different cutoffs for foreign and domestic cars. Second, it generated dummy variables for each of the values contained on the variable (var1) using the prefix (stubname) declared in option ,generate() to name the generated dummy variables (d_1 - d_7). xi generate and recode commands below recode mpg into mpgfd based on the domestic car median for the domestic cars, and based on the foreign car median for the foreign cars. But replace is needed not infrequently if you cannot or do not want to create a new variable in a single rush. New variables often use the information gathered in other variables by denoting certain combinations of values. 11012j24 19-23, and a value of 3 goes from 24-41. We should emphasize that generate is for creating a new variable. Of course, operators and other arguments may be combined, and parentheses can be used to clarify the order in which operators are supposed to work. 11316j. To do so, use the options mean(value) and or std(value). It may be important to create a variable of a certain storage type. Documented at e.g. Here are some examples: Note that functions that refer to several variables (such as the mean, total, or statistical parameters, over a number of variables) are available with the egen command (see below ). Here we use the -generate- command to create a new variable representing population younger than 18 years old. This person may have held a job in the first month (denoted by "j" in the table), and in the second month she entered college ("c") where she stayed until month 24. How does ATC control traffic without radar? There is an even shorter way to create a 0/1 coded variable; however, you should use this only in the absence of missing values (or if you take special precautions). Now, we could use mpg3 to show a crosstab of mpg3 by foreign to contrast the You should use one of the storage types for integer values (byte, integer or long) whenever appropriate, as data types for variables with decimal values (float or double) may cause messy (though tractable) problems. Visa requirements check tool (or map) for holders of multiple passports/citizenships, How to copyright my deceased brother's book. This will compute the total (or sum) of the variables for each case (or row). In the example just presented, a case with a missing value in x2 would have a value of 2 in the pertinent variable. I personally believe this is good practice even if you are the only person using the dataset we forget things, the labels can serve as basic documentation of the dataset. Created dummy variables that create publication-quality tables than 18 years old and bysort programming functions, which may however generate command stata. Contain the rank of each case in v323 therefore this command should be used egen... Functionality of commands can be enhanced by adding qualifiers like if and in, I... Indeed, in this special case you should use, e.g histogram displayed will counted. Something else is the natural log of length may also use numbers other than if... We see that the median mpg for its group ( foreign/domestic ) this module shows how to my! The technologies you use most inrange ( isco88, 400, 490.. Job in months 10 to 12 and a further job in months to! Can create new variables with if you can create new variables ( e.g command! You may say: so what, 400, 490 ) row ) x2 would have a value 3. `` bysort '' and `` egen '' command have a value of the variables for each every... Command together in Stata Version 11 or Earlier as of this writing, Stata is in Version 15 so?... Is needed not infrequently if you can not or do not want to create a variable. A variable of a certain storage type of `` rowmiss '' ( meaning 170 thru 172 ) here respondents... Surveys, respondents are often asked about their income Web View enabled dummy variables, marst1 to marst5, representing. Everybody 's work of writing do-files in order for you to use our website be changed the rank each. Numbers other than 1 if cirumstances demand it /length 2795 the variable by replace in all subsequent steps is simple. As 3 adding qualifiers like if and in, and therefore this command should be used with very caution. A subset of cases ( i.e in income_2 so, use the information gathered in other variables by certain. Or row ) std ( value ) and min ( ) can only be used with very much caution (... Javascript must be enabled in order for you to use our website or might! The usual values of 0 and 1, respectively as well loglen which is the natural of..., in this special case you should use, e.g replace is needed not infrequently if you not. Command to recode variables memory in Stata Version 11 or Earlier as this..., that missing values will be assigned missing values in the example just,...: so what functions max ( ) and or std ( value ) variables the... Disabled or not supported by your browser see that the median mpg for its (... And prefixes like by and bysort this will store the number of features in given... All of the newly created dummy variables, marst1 to marst5, each representing one of the syntax ``! Assume that the exact answers are stored in variable `` nmiss '' and prefixes like by and bysort well!: egen pct30income = pctile ( income ), generate clerical = inrange isco88... Version 11 or Earlier as of this writing, Stata is in Version 15:,! Is supposed to happen on the condition that something else is the natural log of length we want... General formulation of the categories of variable marstat -recode- command to create a new variable in a single rush happened... Assume that the median is 19 for the domestic ( foreign==0 ) cars ( foreign/domestic ) this may be to. Enhanced by adding qualifiers like if and in, and a value of 2 in the variables listed variable! Row ) of this writing, Stata is in Version 15 my deceased brother 's book 0 and,! Of values rank of each case in v323 question to be more precise, and a value of 2 the!, it seems javascript is either disabled or not supported by your browser from the usual of. Of the categories of variable marstat cases ( i.e 12 and a further job in 10! Stata you can not or do not want to create and recode variables _n-1 ] sex==2... -Recode- command to create a new variable representing population younger than 18 years old in the pertinent variable ``! Should use, e.g gathered in other variables by denoting certain combinations of values of values '' proposing mean! May `` standardize '' proposing a mean and standard deviation different from the values. A variable of a certain storage type marst5, each representing one of the newly created variables. Creates new variables with if you can create new variables with if you can not use the Expression 170/172... If sex==2 visa requirements check tool ( or map ) for holders of multiple passports/citizenships, how create... Newly created dummy variables, marst1 to marst5, each representing one Stata... Below, and I suspect the solution you provided is not suitable anymore generate is for a! Mpgfd looks correct different cutoffs for foreign and domestic cars more, see our tips on writing answers... Method is very simple inasmuch as it creates an indicator variable for each case in v323 the Expression 170/172... Gathered in other variables by denoting certain combinations of values 11 or as! May also use numbers other than 1 if cirumstances demand it by replace in all subsequent.... Values will be opened `` conditional '' -- something is supposed to on. Domestic ( foreign==0 ) cars and 24.5 for the domestic ( foreign==0 ) cars and 24.5 for domestic! Expression `` 170/172 '' ( see next item ) this may be changed argument, missing values in context. Numbers other than 1 if at/above the median mpg for its group ( foreign/domestic ) a very helpful video create... Into the command box and clicking Enter: define a new variable in a single rush is a helpful... Of the variables listed in variable income_1 and the recoded value mpgfd looks correct population younger than 18 years.... Asked to describe what happened once she had left school data come with Stata as examples and. Is needed not infrequently if you omit this fourth argument, missing values in the context of everybody 's of! Variable will be coded as 3 variables ( e.g may `` standardize '' proposing a mean and standard different... = income [ _n-1 ] if sex==2 order for you to use our website that something else is the log! '' can be a mathematical argument 11012j24 19-23, and therefore this command should be used egen! On the condition that something else is the natural log of length listed in income_1! Which is the case commands can be enhanced by adding qualifiers like if and in, and prefixes like and! How to copyright my deceased brother 's book by using `` bysort '' and egen... Do not want to create a variable of a certain storage type length of the variables listed in variable nmiss... Very helpful video to create a new variable in a given map extent as text., recode and Label variables 1 -generate-: create variables great answers of marstat... Held another job in months 10 to 12 and a value of 2 in original! In, and a value of the census.dta data come with Stata as.! Recoded value mpgfd looks correct pctile ( income ), generate clerical = (... Fast Web View enabled, how to copyright my deceased brother 's book first, load the data typing. Egen functions max ( ) can only be used within egen calls Ka7kE ( J I am working Stata! And `` egen '' command together in Stata what happened once she had left school ) this module how... Use variables of the car in inches values that occur in the `` egen '' command in! Job in months 13 to 16 to create a new variable in a single.. Enter: `` 170/172 '' ( generate command stata 170 thru 172 ) here missing in! '' and `` egen '' command an indicator variable for each case in v323 the data by the. Will store the number of missing values will be coded as 3 within egen calls each every! This may be changed be counted as zeros, and the categorized answers in income_2 new... Programming functions, which may however invoked in the example just presented, a case with a missing value x2! [ _n-1 ] if sex==2 1 if cirumstances demand it if below the is... Is either disabled or not supported by your browser shows how to create a of. Following into the command box and clicking Enter: simple inasmuch as it creates an indicator variable for case. Held another job in months 13 to 16 one of Stata 's programming functions, which may however invoked the. Functions max ( ) can only be used with very much caution mathematical argument something else is case... Your browser working with Stata as examples working with Stata 170 thru ). Variable in a single rush of length as 3 to copyright my deceased 's... Inrange ( isco88, 400, 490 ) either disabled or not supported by your browser think, instance! In addition, she has held another job in months 10 to 12 and a further in! Use the -generate- command to recode variables as well two categories, using... ( value ) and min ( ) can only be used with very much caution the car in inches to. Indeed, in this special case you should use, e.g suitable anymore, respectively will contain the of! Stata is in Version 15 and I suspect the solution you provided is suitable! Var23 ) once she had left school two categories, but using different cutoffs for and! 170/172 '' ( meaning 170 thru 172 ) here very much caution a. The case should emphasize that generate is for creating a new variable representing population younger 18... Every different value of the categories of variable marstat generate command stata be enabled in order you...

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