Data Analysis

Statistics 6 min One study's medium Cohen's d is compatible with effects from below small to large Cohen's d, Hedges' g and Glass's Δ all divide a difference between two means by a standard deviation, and diff... NA Nadia Rahim 14 Oct Statistics 6 min Division codes from China's Ministry of Civil Affairs survive renames and change with a place's type China's Ministry of Civil Affairs gives province-, prefecture- and county-level units six-digit codes, and all... NA Nadia Rahim 3 Oct Business 5 min What a Spreadsheet Does to Your CSV Twenty-six values through a correct CSV file, into a spreadsheet, and back. Eight came out visibly different,... EV Eva Chin 25 Aug Statistics 5 min Why Your Best Performers Get Worse A thousand simulated pages whose true conversion rates never change. Selected on one period's numbers, the top... NA Nadia Rahim 24 Aug Statistics 5 min What Happens When You Test Twenty Metrics A dashboard rarely shows one number. Simulated with nothing real to find, examining twenty metrics produced at... NA Nadia Rahim 24 Aug Statistics 5 min How Big Does an A/B Test Need to Be? Sample size is usually decided by how long someone will wait. Simulated across a grid, a genuine one-point lif... NA Nadia Rahim 23 Aug Statistics 5 min What Happens When You Check an A/B Test Early Twenty thousand simulated experiments with no real difference in them. Read once at the end, 4.9% came back si... NA Nadia Rahim 23 Aug Statistics 15 min Mean, Median, Mode: The Average Is a Choice, Not a Fact Three different numbers are all correctly called "the average", and which one gets published changes what a re... NA Nadia Rahim 26 Jul Statistics 20 min A High R² Does Not Mean the Model Is Right Anscombe printed one regression summary for four data sets in 1973 and said the features that matter are "invi... NA Nadia Rahim 26 Jul Statistics 17 min Standard Deviation vs Standard Error: Two Numbers, Two Questions Mean ± 4.36 and mean ± 0.97 are not two ways of saying the same thing. Altman and Bland assigned each to a dif... NA Nadia Rahim 26 Jul Statistics 17 min What a 95% Confidence Interval Actually Means Nearly everyone reads a confidence interval as "there is a 95% probability the true value is in here" — includ... NA Nadia Rahim 26 Jul