arnaudbenard/data-science-faq

Aggregation of data science questions

Data science FAQ

This is a personal list of data science questions with their answers

MySQL to Redshift

• concat -> ||
• ifnull -> nvl
• year(col) -> date_part(year, col)

Data

• Latent variables: are variables that are not directly observed but are rather inferred (through a mathematical model) from other variables that are observed (directly measured). Example: result of a PCA https://en.wikipedia.org/wiki/Latent_variable
• One hot encoding: vector with all 0 but one 1. Example: [0, 0, 1, 0] https://en.wikipedia.org/wiki/One-hot

Feature engineering

Calculate feature importance

• Random forest (example)
• Take feature out and check accuracy or Gini values (example)

Models

Deployment