# Difference between revisions of "Iebaltab"

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− | < | + | <code>iebaltab</code> is a Stata command that produces [[Balance tests | balance tables]], or difference-in-means tables, with multiple groups or treatment arms. It is a useful tool to use while [[Sampling & Power Calculations | sampling]], conducting [[Data Analysis | data analysis]] and [[Exporting Analysis | exporting results]] in a reproducible manner. This article outlines the command's features and provides examples for use. |

− | |||

− | + | ==Read First== | |

− | |||

− | == | ||

− | + | *This command is a part of the package <code>[[Stata_Coding_Practices#ietoolkit|ietoolkit]]</code>. To install all the commands in this package including <code>iebaltab</code>, type <code>ssc install ietoolkit</code> in Stata. | |

− | + | * For detailed instructions on how to implement the command in Stata, type <code>help iebaltab</code> in Stata. | |

− | + | ==Overview== | |

− | The command also | + | <code>iebaltab</code> is a Stata command that produces [[Balance tests | balance tables]], or difference-in-means tables, with multiple groups or treatment arms. The command can test for statistically significant differences between either one control group and all other groups or between all groups against each other. The command also allows for fixed effects, covariates and different types of variance estimators. |

− | + | <code>iebaltab</code> issues helpful error messages if the command is mis-specified or if the nature of the data leaves the potential for the results to be misinterpreted or invalid. For example, if an observation has a missing value in a variable used in an F-test for joint significance, then Stata cannot do anything but drop that observation. The command will issue an error unless the user specifies the option to suppress the error or specifies an option that tells the command how to interpret missing values. | |

− | + | The command attaches notes to the bottom of the table with information on, for example, which significance levels are used for stars, which fixed effects or covariates that were included (if any) etc. | |

− | |||

− | + | ==Implementation== | |

− | + | This section outlines the basic functionalities of the command -- estimating descriptive stats, t-tests, and F-tests -- with sample code. | |

− | === | + | ===Generating Descriptive Stats=== |

− | |||

− | < | + | <nowiki>reg balancevarname if groupvar = groupcode</nowiki> |

− | + | where ''balancevarname'' refers to the variables (one at a time) listed in ''balancevarlist'', ''groupvar'' refers to the variable listed in the option '''grpvar'''(''varname''), and ''groupcode'' refers to the value corresponding to the group for which the means and standard errors are estimated. _b[cons] from the returned results is the group mean and _se[cons] is the standard error in the group mean. Fixed effects and covaraiates are never included in this regression. | |

− | + | ===Running t-tests=== | |

− | + | ||

+ | <nowiki>reg balancevarname testgroupdummy | ||

+ | test testgroupdummy </nowiki> | ||

− | + | where ''testgroupdummy'' is a dummy with the value 0 for one of the groups compared in the t-test and 1 for the other group. r(p), from the returned results, is used when adding stars to the tables according to the thresholds specified in option starlevels(). | |

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− | |||

− | + | ===Running F-tests=== | |

− | < | + | <nowiki>reg testgroupdummy balancevarlist |

+ | testparm balancevarlist</nowiki> | ||

where r(p), from the returned results, is used when adding stars to the tables | where r(p), from the returned results, is used when adding stars to the tables | ||

according to the thresholds specified in option starlevels(). | according to the thresholds specified in option starlevels(). | ||

− | ===Fixed | + | ===Including Fixed Effects=== |

− | + | <nowiki>xi : reg balancevarname testgroupdummy i.fixed | |

− | + | test testgroupdummy | |

+ | xi : reg testgroupdummy balancevarlist i.fixed | ||

+ | testparm balancevarlist </nowiki> | ||

− | + | where ''fixed'' refers to the variable included as the fixed effects in option fixedeffects(). | |

− | + | ===Including Covariates=== | |

− | < | + | <nowiki>reg balancevarname testgroupdummy covariatesvarlist |

+ | test testgroupdummy | ||

+ | reg testgroupdummy balancevarlist covariatesvarlist | ||

+ | testparm balancevarlist </nowiki> | ||

+ | where ''covariatesvarlist'' refers to the variables inlcuded as the control variables in option covariates(). | ||

− | + | ===Including Non-Default Variance Estimators=== | |

− | + | <nowiki>reg balancevarname testgroupdummy, vce(vcetype) | |

+ | test testgroupdummy | ||

+ | reg testgroupdummy balancevarlist, vce(vcetype) | ||

+ | testparm balancevarlist</nowiki> | ||

− | + | where ''vcetype'' is the variance estimator specified. | |

− | + | ===Combining Them All=== | |

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− | ===Combining | ||

All options described above can be included in the same regression, for example: | All options described above can be included in the same regression, for example: | ||

− | < | + | <nowiki>xi : reg balancevarname testgroupdummy i.fixed covariatesvarlist, vce(vcetype) |

− | + | test testgroupdummy </nowiki> | |

− | test testgroupdummy </ | ||

==Examples== | ==Examples== | ||

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===Example 1=== | ===Example 1=== | ||

− | < | + | <nowiki>ebaltab {it:outcome_variable}, grpvar({it:treatment_variable}) browse </nowiki> |

In the example above, let's assume that ''treatment_variable'' is a variable that is 0 for observations in the control group, and 1 for observations in the treatment group. Then in this example, the command will show the mean of {it:outcome_variable} and the standard error of that mean for the control group and the treatment group separately, and it will show the difference between the two groups and test if that difference is statistically significant. | In the example above, let's assume that ''treatment_variable'' is a variable that is 0 for observations in the control group, and 1 for observations in the treatment group. Then in this example, the command will show the mean of {it:outcome_variable} and the standard error of that mean for the control group and the treatment group separately, and it will show the difference between the two groups and test if that difference is statistically significant. | ||

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===Example 2=== | ===Example 2=== | ||

− | < | + | <nowiki>global project_folder "C:\Users\project\baseline\results"} |

− | + | iebaltab ''outcome_variable'', grpvar(''treatment_variable'') /// | |

− | iebaltab ''outcome_variable'', grpvar(''treatment_variable'') save("$project_folder\balancetable.xlsx")} </ | + | save("$project_folder\balancetable.xlsx")} </nowiki> |

− | + | Here, the table is saved to file instead of being shown in the browser window as in Example 1. | |

===Example 3=== | ===Example 3=== | ||

− | < | + | <nowiki>iebaltab ''outcome1 outcome2 outcome3'', grpvar(''treatment_variable'') /// |

+ | save("$project_folder\balancetable.xlsx") /// | ||

+ | rowlabels("outcome1 Outcome variable 1 @ outcome2 Second outcome variable")</nowiki> | ||

− | + | Here, there are now three variables listed as balance variables. In option ''rowlabels()'', two of those balance variables are given a row label to use in lieu of the variable name. Instead of outcome1 and outcome2, the row titles will read "Outcome variable 1 and "Second outcome variable," respectively. Since outcome3 is not otherwise specified in ''rowlabels()'', the command will use outcome3’s variable name as the row title. | |

== Back to Parent == | == Back to Parent == | ||

+ | |||

This article is part of the topic [[Stata Coding Practices]] | This article is part of the topic [[Stata Coding Practices]] | ||

+ | ==Additional Resources== | ||

+ | *DIME Analytics' [https://github.com/worldbank/DIME-Resources/blob/master/stata2-6-descriptives.pdf Descriptive Statistics: Creating Tables] | ||

+ | *Read more about <code>ietoolkit</code> [https://github.com/worldbank/ietoolkit here] on GitHub | ||

+ | [[Category: Stata]] |

## Latest revision as of 21:32, 10 September 2020

`iebaltab`

is a Stata command that produces balance tables, or difference-in-means tables, with multiple groups or treatment arms. It is a useful tool to use while sampling, conducting data analysis and exporting results in a reproducible manner. This article outlines the command's features and provides examples for use.

## Read First

- This command is a part of the package
`ietoolkit`

. To install all the commands in this package including`iebaltab`

, type`ssc install ietoolkit`

in Stata. - For detailed instructions on how to implement the command in Stata, type
`help iebaltab`

in Stata.

## Overview

`iebaltab`

is a Stata command that produces balance tables, or difference-in-means tables, with multiple groups or treatment arms. The command can test for statistically significant differences between either one control group and all other groups or between all groups against each other. The command also allows for fixed effects, covariates and different types of variance estimators.

`iebaltab`

issues helpful error messages if the command is mis-specified or if the nature of the data leaves the potential for the results to be misinterpreted or invalid. For example, if an observation has a missing value in a variable used in an F-test for joint significance, then Stata cannot do anything but drop that observation. The command will issue an error unless the user specifies the option to suppress the error or specifies an option that tells the command how to interpret missing values.

The command attaches notes to the bottom of the table with information on, for example, which significance levels are used for stars, which fixed effects or covariates that were included (if any) etc.

## Implementation

This section outlines the basic functionalities of the command -- estimating descriptive stats, t-tests, and F-tests -- with sample code.

### Generating Descriptive Stats

reg balancevarname if groupvar = groupcode

where *balancevarname* refers to the variables (one at a time) listed in *balancevarlist*, *groupvar* refers to the variable listed in the option **grpvar**(*varname*), and *groupcode* refers to the value corresponding to the group for which the means and standard errors are estimated. _b[cons] from the returned results is the group mean and _se[cons] is the standard error in the group mean. Fixed effects and covaraiates are never included in this regression.

### Running t-tests

reg balancevarname testgroupdummy test testgroupdummy

where *testgroupdummy* is a dummy with the value 0 for one of the groups compared in the t-test and 1 for the other group. r(p), from the returned results, is used when adding stars to the tables according to the thresholds specified in option starlevels().

### Running F-tests

reg testgroupdummy balancevarlist testparm balancevarlist

where r(p), from the returned results, is used when adding stars to the tables according to the thresholds specified in option starlevels().

### Including Fixed Effects

xi : reg balancevarname testgroupdummy i.fixed test testgroupdummy xi : reg testgroupdummy balancevarlist i.fixed testparm balancevarlist

where *fixed* refers to the variable included as the fixed effects in option fixedeffects().

### Including Covariates

reg balancevarname testgroupdummy covariatesvarlist test testgroupdummy reg testgroupdummy balancevarlist covariatesvarlist testparm balancevarlist

where *covariatesvarlist* refers to the variables inlcuded as the control variables in option covariates().

### Including Non-Default Variance Estimators

reg balancevarname testgroupdummy, vce(vcetype) test testgroupdummy reg testgroupdummy balancevarlist, vce(vcetype) testparm balancevarlist

where *vcetype* is the variance estimator specified.

### Combining Them All

All options described above can be included in the same regression, for example:

xi : reg balancevarname testgroupdummy i.fixed covariatesvarlist, vce(vcetype) test testgroupdummy

## Examples

### Example 1

ebaltab {it:outcome_variable}, grpvar({it:treatment_variable}) browse

In the example above, let's assume that *treatment_variable* is a variable that is 0 for observations in the control group, and 1 for observations in the treatment group. Then in this example, the command will show the mean of {it:outcome_variable} and the standard error of that mean for the control group and the treatment group separately, and it will show the difference between the two groups and test if that difference is statistically significant.

### Example 2

global project_folder "C:\Users\project\baseline\results"} iebaltab ''outcome_variable'', grpvar(''treatment_variable'') /// save("$project_folder\balancetable.xlsx")}

Here, the table is saved to file instead of being shown in the browser window as in Example 1.

### Example 3

iebaltab ''outcome1 outcome2 outcome3'', grpvar(''treatment_variable'') /// save("$project_folder\balancetable.xlsx") /// rowlabels("outcome1 Outcome variable 1 @ outcome2 Second outcome variable")

Here, there are now three variables listed as balance variables. In option *rowlabels()*, two of those balance variables are given a row label to use in lieu of the variable name. Instead of outcome1 and outcome2, the row titles will read "Outcome variable 1 and "Second outcome variable," respectively. Since outcome3 is not otherwise specified in *rowlabels()*, the command will use outcome3’s variable name as the row title.

## Back to Parent

This article is part of the topic Stata Coding Practices

## Additional Resources

- DIME Analytics' Descriptive Statistics: Creating Tables
- Read more about
`ietoolkit`

here on GitHub