Data validation is an essential part of any data handling task, whether you're in the field gathering information, analyzing data, or preparing to present data to stakeholders. If your data isn't correct from the start, your results will be as well. As a result, data must be verified and validated before it can be used.
While data validation is an essential step in any data workflow, it is frequently overlooked. Data validation may appear to be a step that slows down your work pace, but it is critical because it will help you produce the best results possible. Nowadays, data validation can be a much faster process than you might think.
Validation can be treated as an essential component of your workflow rather than an afterthought with data integration platforms that can incorporate and automate validation processes.
What is Data Validation?
The process of verifying and validating data before it is used is known as data validation. To ensure accurate results, any type of data handling task, whether it is gathering data, analyzing it, or structuring it for presentation, must include this process.
It can be tempting to avoid validation because it takes time. However, it is a necessary step in achieving the best results possible. A system includes several checks to ensure that the data being entered and stored is logically consistent. Data Validation is now much faster thanks to technological advancements.
The majority of data integration platforms incorporate and automate the data validation step, making it an inherent step in the overall workflow rather than an additional one. There is little need for human intervention in such automated systems.
Data validation becomes necessary because poor-quality data causes problems downstream, and cleansing data later in the process incurs higher costs.
Within organizations that deal with data and its collection, processing, and analysis, the data validation process has grown in importance. It is regarded as the foundation for effective data management because it enables analytics based on meaningful and valid datasets.
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How to perform Data Validation?
A spreadsheet program, such as Microsoft Excel or Google Sheets, is one of the most basic and common ways that data is used. The data validation process is a simple, built-in feature in both Excel and Sheets. More about excel you can learn on Microsoft Excel courses.
Data > Data Validation is a menu item in both Excel and Sheets. A user can select the specific data type or constraint validation required for a given file or data range by selecting the Data Validation menu.
Data validation policies are typically integrated into ETL (Extract, Transform, and Load) and tools of data integration to be executed as data is extracted from one source and loaded into another. Popular open-source tools, such as debt, include data validation capabilities and are frequently used for data transformation.
Data validation for an input value can also be done programmatically in an application context. A script, for example, can check an input variable, such as a password, as it is sent to ensure it meets constraint validation for the correct length.
Why Validate Data?
Validation is critical for data scientists, analysts, and others who work with data. Any given system's output can only be as good as the data on which it is based. Machine learning or AI models, data analytics reports, and business intelligence dashboards are examples of such operations.
Validating the data ensures that it is accurate, which means that all systems that rely on it will be as well. Data validation is also required for data to be useful for an organization or a particular application operation. For example, if data is not in the correct format for a system to consume, it cannot be used easily, if at all.
As data moves from one location to another, different data requirements emerge depending on the context in which the data is used. Validation of data ensures that it is correct for specific contexts. Data validation of the proper type makes the data useful.
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Types of Data Validation
Every organization will have its own set of rules for data storage and maintenance. Setting basic data validation rules will help your company maintain organized standards, making data work more efficient.
The majority of data validation procedures will perform one or more of these checks to ensure that the data is correct before it is stored in the database. There are numerous kinds of data validation. Before storing data in a database, most data validation procedures will perform one or more of these checks to ensure that it is correct.
The following are examples of common data validation checks:
Checking the Data Type
A data type check verifies that the information entered is of the correct data type. A field, for example, might only accept numeric data. If this is the case, the system should reject any data that contains other characters such as letters or special symbols.
Check Your Code
A Code Check verifies that a field is selected from a valid list of options or that certain formatting rules are followed. For example, comparing a postal code to a list of valid codes makes it easier to verify its authenticity. Country codes and NAICS industry codes, for example, can be approached in the same manner.
Check the Range
A Range Check determines whether the input data falls within a specified range. In geographic data, for example, latitude and longitude are frequently used. The latitude should be between -90 and 90 degrees, and the longitude should be between -180 and 180 degrees. Any values that fall outside of this range are deemed invalid.
Many data types have a standard format. A format check ensures that the data is correctly formatted. Date fields, for example, are stored in a consistent format, such as "YYYY-MM-DD" or "DD-MM-YYYY." The date will be rejected if it is entered in any other format. A national insurance number appears as follows: LL 99 99 99 L, where L is any letter and 9 is any number.
Check for Consistency
A consistency check is a type of logical check that ensures data is entered consistently. One example is checking to see if a parcel's delivery date is after the shipping date.
Check for Individuality
Some information, such as IDs and email addresses, is inherently unique. These database fields should most likely have unique entries. A Uniqueness Check ensures that an item is not duplicated in a database.
Check for Presence
A presence check ensures that no required fields are left blank. If a user attempts to leave the field blank, an error message will be displayed, and they will be unable to proceed to the next step or save any other data that they have entered. A key field, for example, cannot be left blank in most databases.
Check the Length
A Length Check ensures that the correct number of characters are entered into the field. It ensures that the entered character string is neither too short nor too long. Consider a password that must be at least 8 characters long. The Length Check ensures that the field contains exactly 8 characters.
Look it Up
Look Up helps to reduce errors in a field with a limited set of values. It consults a table to determine acceptable values. The fact that there are only 7 possible days in a week, for example, ensures that the list of possible values is limited.
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Steps of Data Validation
Data validation steps are as follows:
Select a data sample
Choose the data to sample. If you have a large amount of data, you should probably validate a subset of it rather than the entire set. To ensure the success of your project, you must decide how much data to sample and what error rate is acceptable.
Verify the Database
Before you move your data, make sure that all of the necessary information is in your existing database. Determine the number of records and unique IDs, as well as a comparison of the source and target data fields.
Check the Data Format
Determine the overall health of the data and the changes that will be required to the source data in order for it to match the schema in the target. Then look for inconsistencies or missing counts, duplicate data, incorrect formats, and null field values.
Methods of Data Validation
You can validate data in one of the following ways:
Scripting: Data validation is commonly performed by writing scripts for the validation process in a scripting language such as Python. You can, for example, create an XML file containing the source and target database names, table names, and columns to compare.
The Python script can then read the XML and process the results. However, because you must write the scripts and manually verify the results, this can be time-consuming.
Enterprise tools: Enterprise tools are available to perform data validation. For example, FME data validation tools can validate and repair data. Enterprise tools are more stable and secure, but they require infrastructure and are more expensive than open-source alternatives.
Open source tools: Open source options are cost-effective, and if cloud-based, they can also save you money on infrastructure costs. However, they still necessitate some level of knowledge and hand-coding to be used effectively. SourceForge and OpenRefine are examples of open source tools.
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Benefits and Drawbacks of Data Validation
Below are the benefits and drawbacks of data validation :
Ascertain that the data is clean and error-free: When it comes to ensuring data integrity, data validation does a lot of the heavy lifting. While it will not transform or enrich your data, validation will ensure that it fits its intended purpose if properly configured.
Aids in the Management of Multiple Data Sources: The more data sources you use, the more critical data validation becomes. Assume you're importing customer data from multiple channels; you'll need to validate all of that data against the same tracking plan at the same time. Otherwise, disparities and errors between datasets may occur.
Save Time: While data validation takes time, once completed, you will not need to make any changes until your inputs or requirements change. As the preceding examples demonstrate, this saves both time and money.
Proactive Strategy: Data validation is proactive, attempting to iron out problems before they enter more complex systems. By validating data before using it in any way, you ensure the functionality of all downstream systems, both now and in the future.
Drawbacks to Data Validation:
Complexity: Validation is a difficult task when dealing with multiple sources of complex data. Automated tools can help in this situation, and many enterprise platforms, such as Segment, include powerful validation tools for large multi-source applications.
Data Validation Errors: Data validation can result in errors, and not all validation software is perfect. There will almost certainly be validation errors that must be addressed.
Time: When time is of the essence, it may be tempting to skip data validation. It may be tempting to ignore data validation in seemingly simple applications, but keep in mind that those applications may grow in the future.
Changing Needs: One of the most significant disadvantages of data validation is that data must be re-validated once specific changes to the data are made. As new data types and inputs are added, schema models and mapping documentation will need to be updated.
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Lastly, Data validation is time well spent. Once you've created a tracking plan, make a note of the data types you'll be using and the expected values. Building conforming ingestion pipelines will become much easier if you do this.
While tools like Pydantic are great for bespoke data validation in many cases, validation software greatly simplifies the process of validating data ingested from multiple sources using different techniques and with different entities, properties, and events.