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Stony Brook University

Data Cleaning and Wrangling Guide

Essential techniques and best practices for preparing ready-to-use data, with implementation examples in Google Sheets, Microsoft Excel, Python, and R.

Welcome!

This guide provides information on essential techniques for preparing data for analysis, including handling missing values, removing duplicates, and transforming data. It provides practical examples and best practices to ensure your data is accurate and ready for analysis. It also covers how to implement these techniques using tools like Google Sheets, Microsoft Excel, Python, and R, making it suitable for both beginners and experienced users.

Why Data Cleaning and Data Wrangling?

In any data-driven project, raw data often arrives in a messy, unstructured state, filled with errors, inconsistencies, and missing values. Attempting to analyze such data without first addressing these issues can lead to inaccurate conclusions, wasted time, and ultimately, flawed decision-making.

Data Cleaning
The process of identifying and correcting these errors, inconsistencies, and inaccuracies in your dataset. This can involve handling missing values, removing duplicates, and standardizing formats. Proper data cleaning ensures that your dataset is accurate, consistent, and ready for reliable analysis.
 
Data Wrangling
Also known as data munging, it involves transforming and organizing raw data into a more usable format. This includes reshaping data, merging multiple datasets, and applying various transformations to make the data easier to analyze. Effective data wrangling is essential for structuring your data in a way that maximizes the insights you can gain from it. It streamlines the analytical process, making it more efficient and allowing you to focus on extracting meaningful information.
 

In short, data cleaning addresses issues within a dataset, ensuring its accuracy and completeness. Data wrangling, meanwhile, reorganizes the data into a format that is easier to work with, enabling more effective analysis and better decision-making. Both of them are indispensable steps in preparing data for analysis, ensuring that the final insights are based on reliable, well-structured information.