
Sample Ratio Mismatch (SRM): How to Detect It
Many product decisions in online companies rest on A/B tests. We show one version of the website to one group

Many product decisions in online companies rest on A/B tests. We show one version of the website to one group

A supermarket chain runs a loyalty program across 180 stores. The program has been live for almost two years, and

In 2012, eBay switched off its paid brand search ads on Yahoo and MSN and watched what happened to sales.

Every statistics handbook covers confidence intervals. And everyone who has ever studied statistics has been confused by the fact that

Some of the most important analytics decisions are made without an A/B test. For example, a marketing campaign can be

A supermarket chain runs a loyalty program across 180 stores. The program has been live for almost two years, and

Some of the most important analytics decisions are made without an A/B test. For example, a marketing campaign can be

When Amazon Prime launched in 2005, it changed delivery costs from a transaction cost into a membership benefit, something customers

Every analyst has stared at a dashboard showing a seemingly clear pattern, time and again. Premium customers churn more, marketing

The most important question in almost any organisation is also the hardest: Did something work? You launch a new feature, a

Marketing teams often celebrate when dashboards show a clear, positive correlation between sales and advertising activity. Applying the Frisch-Waugh-Lovell theorem

Estimating the effect of one variable on another is central to causal inference. However, observational data can make this challenging,

Difference-in-Differences (DiD) is a widely used technique to estimate causal effects when randomised experiments are not feasible. From policy evaluation

In the world of marketing, deciding which customers to target with specific promotions can feel like a never-ending puzzle — especially when

Evaluating the impact of treatments or interventions is critical in various fields, including business and healthcare. Determining whether a specific