Data cleaning is one of the most crucial aspects of data science and machine learning. It is crucial in the construction of a model. It isn’t the most glamorous aspect of machine learning, but there aren’t any hidden tricks or secrets to discover. However, proper data cleaning determines whether a project succeeds or fails. Because “better data beats fancier algorithms,” professional data scientists typically devote significant effort to this step.
If we start with a clean dataset, there’s a strong chance we’ll be able to produce good results using basic techniques, which can be quite useful in terms of computing, especially when the dataset is enormous. Different sorts of data will, of course, necessitate different types of cleansing. On the other hand, this systematic approach might always serve as a decent beginning point.
Before diving into the data cleaning steps, let’s first understand its meaning.
What Is Data Cleaning, and Why is it important?
The process of editing, revising, and organizing data within a data set to be uniform and ready for analysis is known as data cleaning. This includes eliminating any incorrect or useless data and formatting it in a computer-readable way for the best possible analysis.
Data cleaning is a time-consuming procedure, but it’s necessary if you want to get the best results and insights from your data.
Data scientists agree that better data is more crucial than the most sophisticated algorithms in machine learning. This is because machine learning models are only as good as the data they’re trained on. If you use faulty data to train your models, the eventual results will be untrustworthy in general and potentially hazardous to your company.
Proper data cleaning will save you time and money while increasing the efficiency of your business. It will also allow you to target different markets and groups more effectively and use the same data sets for multiple analyses and downstream operations.
Steps involved in Data Cleaning:
Removal of unwanted observations
This includes removing variables from your dataset that are duplicate, redundant, or irrelevant. Duplicate observations are common throughout data gathering, and irrelevant observations are ones that don’t pertain to the problem you’re attempting to answer.
Redundant observations reduce efficiency by a significant amount because the data repeats and can add to the right or wrong side, resulting in inconsistent results.
Any data that is of no benefit to us and may be eliminated directly is considered irrelevant.
Fix structural errors
Misspellings, inconsistencies in name standards, erroneous capitalization, incorrect word usage, and other structural faults are examples of structural errors. While these errors may be obvious to humans, most machine learning systems will not, and your analyses will be skewed.
For example, You’d have to standardize the title if you were analyzing two different data sets, one with a ‘women’ column and the other with a ‘female’ column. Dates, addresses, phone numbers, and other information must also be standardized in order for computers to interpret them
Managing Unwanted outliers
With some sorts of models, outliers can cause problems. In comparison to decision tree models, linear regression models are less resistant to outliers. Outliers should generally not be removed unless there is a compelling cause to do so. Taking them away increases performance in certain cases but not in others. As a result, there must be a compelling cause to discard the outlier, such as suspicious values that are unlikely to be seen in real data.
Handling missing data
In machine learning, missing data is a deceptively difficult problem to solve. We can’t merely disregard or delete the observation that’s missing. They must be handled with caution since they may indicate something significant.
The two common ways to deal with missing data are:
1)Dropping observations with missing values:
It’s possible that the fact that the value was missing was instructive in and of itself.
Furthermore, in the real world, you will frequently be required to generate predictions based on new data, even if some features are lacking!
2) Imputing the missing values from past observations:
Again, “missingness” is nearly always instructive in and of itself, and you should alert your algorithm if a value is missing.
Even if you create a model to infer your values, you won’t be adding any real data. You’re only reinforcing patterns that other features have already established.
It’s like missing a piece of a puzzle when data is absent. Dropping it is equivalent to pretending the puzzle slot does not exist. If you infer it, it’s as if you’re trying to fit a piece from another puzzle into your puzzle.
As a result, missing data is usually instructive and suggestive of something significant. By highlighting missing data, we must also be aware of our algorithm. Instead of filling in the missingness with the mean, you can use this strategy of flagging and filling to allow the algorithm to determine the best constant.
Validate your data
Data validation is the last step in the data cleaning process, and it ensures that your data is of good quality, consistent, and formatted properly for downstream processing.
Do you have enough information to meet your requirements?
Is it formatted consistently in a design or language your analytic software can understand?
Does your unprocessed data quickly support or refute your hypothesis?
Verify that your data is well-organized and clean enough for your requirements. Verify that no data points are missing or incorrect by cross-checking the related data points.
Data Cleaning Tools:
Machine learning and artificial intelligence (AI) tools can ensure that your data is accurate and ready for usage. You can use data wrangling techniques and tools to help automate the process once you’ve completed the necessary data cleaning procedures.
Some data cleansing tools
IBM Infosphere Quality Stage
So far, we’ve gone through data cleaning methods that might help you make your data more dependable and get better results. We’ll have a strong dataset that avoids many of the most common errors if we properly complete the Data Cleaning stages. This stage should not be skipped because it is crucial for the rest of the data science procedure.
To know more about data cleaning and other methods involved in a data science project, enrol in Learnbay’s Data Science Course in Canada. Learn various data science skills and leverage them in several data sciences projects guided by industry experts.