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Correlation and causation

You may have heard the phrase ‘correlation does not imply causation’ or ‘correlation is not causation’, but what does this mean? Earlier, you saw how two variables can be correlated, …

Querying a database

Querying involves requesting to access data from a database to retrieve it or manipulate it. The SELECT statement is the most commonly used SQL statement for querying data in a …

Database fundamentals

As an analyst you’ll often work with databases, especially when you have to analyse business data or transactions. This video covers the basic information about databases that you must know …

Introduction to SQL

Structured Query Language (SQL) is the most widely implemented database query language and is supported by many popular relational database systems, including: MS SQL Server, IBM DB2, MySQL, and Microsoft …

Calculating correlation with spreadsheets

To calculate the correlation in an Excel spreadsheet, you can use the CORREL() function. Let’s look at an example. Consider these two lists of data in an Excel spreadsheet: To …

How to Filter Query Results in SQL

Being able to retrieve a set of columns from a database is useful, but we don’t really begin to leverage the power of SQL until we start to filter specific …

Diagnostic techniques

Any diagnostic technique’s main purpose is basically to discover the root cause of the problem or event you have discovered. There are a few methods that can be employed in …

Pearson’s correlation coefficient

Pearson’s correlation coefficient ((r)) is used to describe the correlation between two variables with a linear relationship. (r) varies from -1 to +1, where: -1 represents a strong, negative correlation …