The number of individual scores that can vary without changing the sample mean is known as what? Statistically written as 'N-1' where N is the number of subjects.

• A. Degrees of freedom
• B. Deviation
• C. Discrete variable
• D. Dispersion

Answer: (A)

Degrees of freedom describe how many values in a calculation can vary independently while still satisfying known constraints. In a set of N scores, once the mean is fixed, knowing N−1 of the scores leaves the last one determined by the required total. So there are N−1 independent pieces of information, or degrees of freedom. This concept explains why estimating population variance from a sample uses N−1 in the denominator (Bessel’s correction) to get an unbiased estimate. The other terms describe spread (dispersion), a type of variable (discrete), or a distance from the mean (deviation) but don’t capture the idea of how many independent values can vary given a fixed mean.