Stats hw qs Quiz 2
What is the 50th percentile called?
Median
What is the primary disadvantage of using the range to compare the variability of data sets?
It is a rather insensitive measure of data variation.
Define QL
The lower quartile, QL, is the 25th percentile of a data set.
Describe the sample variance using words rather than a formula. Do the same with the population variance.
The sample variance is the sum of the squared deviations from the mean divided by the number of measurements minus one. The population variance is the average of the squared distances of the measurements on all units in the population from the mean.
Define QU
The upper quartile, QU, is the 75th percentile of a data set.
Can the variance of a data set ever be negative? Explain. Can the variance ever be smaller than the standard deviation? Explain.
The variance of a data set cannot be negative because it is the sum of the squared deviations divided by a positive value. Variance can be smaller than the standard deviation if the variance is less than 1.
