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Posts Tagged ‘data management’

Data management made easy

Data management and data cleaning are critically important steps in any data analysis. Many of us learned this lesson the hard way. Have you ever fit a model that includes age as a covariate and forgotten to convert the missing value codes of -99 to missing values? I have. Or maybe you overlooked a data entry error that resulted in an age of 354 that should have been 54. I’ve done that too. Careful data management and cleaning can help us avoid these kinds of embarrassing mistakes.

I recently recorded a series of data management videos for the Stata Youtube Channel. You can click on the links below to watch the videos. I included topics that I think are important, but the list is far from exhaustive. If you would like to see videos on additional topics, please leave your suggestion in the comments below.

Data management playlist

You can learn more about these topics and many others in the Data Management Reference Manual.

Handling gaps in time series using business calendars

Time-series data, such as financial data, often have known gaps because there are no observations on days such as weekends or holidays. Using regular Stata datetime formats with time-series data that have gaps can result in misleading analysis. Rather than treating these gaps as missing values, we should adjust our calculations appropriately. I illustrate a convenient way to work with irregularly spaced dates by using Stata’s business calendars.

In nasdaq.dta, I have daily data on Read more…

A tour of datetime in Stata

Converting a string date

Stata has a wide array of tools to work with dates. You can have dates in years, months, or even milliseconds. In this post, I will provide a brief tour of working with dates that will help you get started using all of Stata’s tools.

When you load a dataset, you will notice that every variable has a display format. For date variables, the display format is %td for daily dates, %tm for monthly dates, etc. Let’s load the wpi1 dataset as Read more…