SQL Correlation With Pandas | Dataford Interview Questions

Use Python and Pandas to calculate correlation.

For this SQL version, calculate the Pearson correlation between x_value and y_value for each category. Exclude incomplete pairs, but retain categories with no valid pairs.

Output

One row per category
Columns: category_name, pearson_correlation, and valid_observations
Include categories with no valid observations, with a NULL correlation and a count of zero
Order by category_id ascending

Schema

correlation_categories

Column	Type	Description
category_idPK	INT	Unique category identifier
category_name	VARCHAR(100)	Category label

correlation_observations

Column	Type	Description
observation_idPK	INT	Unique observation identifier
category_id	INT	Category associated with the observation
x_value	DECIMAL(10,2)	First numeric variable
y_value	DECIMAL(10,2)	Second numeric variable

Your question is SQL Correlation With Pandas. Start with the requirements and the two tables in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem