How data cleaning happens: stages

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The chosen method must be able to clean the sample from errors, both if it is collected from one source and if the data is taken from different channels. It is important that this method is supported by the tools the specialist works with and can adapt to changes, such as other data sources.

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The cleaning steps listed here are approximate. Depending on the sample, cleaning method, and other factors, the process may vary. This example is intended to give an idea of ​​what the cleaning process looks like in general.

Data analysis. Before cleaning, the specialist analyzes the sample to understand how polluted it is and what errors it contains. He can partially analyze it manually, but usually special services are used for this — they determine and display the properties of the data in the sample. For example, they show the range of values ​​in the "Price" field: abnormal values ​​will be visible immediately.

Designing the process. Once the specialist has cayman islands telegram data metadata—that is, data about the data—he can decide how exactly he will clean the sample. At this stage, he determines what transformations will be needed, what rules and methods to use.

Transformations. The specialist uses tools or writes scripts that change the data. The most important thing is to set the logic. For example, automated DBMS tools can perform transformations themselves if you specify the rules for them. But for this, the transformations must be clearly described.

In addition, if exact values ​​are needed for some erroneous data, they sometimes have to be obtained manually. For example, re-requesting a large amount of information that was transmitted incorrectly.

Verification. The specialist must ensure that the transformations are performed correctly. Therefore, even before working with the full selection, he can test the script or set of rules on a small group of records. This will help him to ensure that the cleaning is performed correctly. And if errors are found in the logic, they can be eliminated.