When the squared deviations are averaged, which divisor is used for a sample and which for a population?

1. A population variance divides the sum of squared deviations by N, the number of items in the population. 2. A sample variance has to use an estimated mean rather than the real population mean. 3. Dividing by n minus one rather than n corrects for that and gives a better estimate of the population variance. 4. Swapping the two divisors is the common slip, and it makes the sample estimate too small. _Source: OpenStax Introductory Business Statistics (CC BY 4.0), Ch 2 "Descriptive Statistics", section 2.7 Measures of the Spread of the Data_