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What is Z Test in Hypothesis Testing | Data Science Interview Questions and Answers

https://thinkingneuron.com/data-scien... Z-Test is same as T-Test. We use Z-Test when the sample size is MORE than 30 and otherwise T-test is used. The t-test is used when the sample size is LESS than 30. In Z-test, if the variance σ is not known, then it is approximated using the sample values as sd/√(n). Z-score can be calculated from the following formula. z = (X – μ) / σ Where z is the z-score, X is the value of the element, μ is the population mean, and σ is the standard deviation.