Z-test

A Z-test is a statistical method used to determine if there's a significant difference between a sample average and a known population average, assuming the population’s variability is known. It helps assess whether observed results are likely due to chance or indicate a real difference. For example, it can be used to see if a new teaching method truly improves test scores compared to historical averages. The Z-test calculates a score (the Z-value) that shows how many standard deviations the sample mean is from the population mean, allowing us to decide if the difference is statistically meaningful.