Range
The distance covered by scores in a distribution, smallest to largest
Ex:range from 2 to 8, 8-2 is 6
Interquartile Range
A measure of distance between the 1st Q (25th percentile) and 3rd Q (75th percentile) which is the range for the middle 50% of data set
Variance
The average of squared deviations from the mean
Standard Deviation
The square root of the average of squared deviations from the mean
Unbiased Statistic
If the average value of the statistic is equal to the population parameter
Biased Statistic
If the average value of the statistic under or over estimates the population parameter
Degrees of Freedom
They determine the number of scores in the sample that are independent and vary.
Ex:You have 4 scores, mean is 5, 3 values are 4,6,7. You can determine that the final score is 3 or the mean wouldn’t be 5.
