PSYC1040 Central Tendency

The skewness of a distribution refers to its:

• flatness

• peakedness

• symmetry

• central tendency

• variability

What does a positively skewed distribution typically have?

• A long tail above the median, along with most of its scores

• A long tail below the mean, along with most of its scores

• Most of its scores between the 50th and 90th percentile

• Most of its scores below the median

• A long tail above the mean and most of its scores below the mean

A distribution of scores has a mean of 12, a mode of 18, and a median of 16. The distribution is:

• normal

• positively skewed

• negatively skewed

• rectangular

• U-shaped

One of the reasons the mean is the preferred measure of central tendency is because:

• it's the easiest to calculate

• sometimes there isn't a median

• it is the basis of many subsequent calculations, like variance and SD

• it is always a good measure of central tendency

• all of the above

The variance is:

• the average distance of scores from the mean

• the standard distance of scores from the mean

• the largest deviation of the scores from the mean

• the average squared distance of scores from the mean

• the smallest deviation of the scores from the mean

Which of the following does not apply to the standard deviation?

• It is a measure of variability

• It is an intuitive description of a dataset's variability

• It is a measure of the amount by which scores deviate from the median

• It is the square root of the variance

• It is a measure of the amount by which scores deviate from the mean

Calculate the average distance of the following scores from their mean:

2 3 4 1 2 3 4 1 5 5 6 2 3 2 4 5 6 2 2 1 3 3 4 5 6 7 7 8 5 4 3 3 2 3 4

• 0

• .5

• 1

• 1.5

• 2

What is the median of the following data set?

21 23 23 23 24 25 26 27 29 30 38 44 52

• 31

• 26

• 23

• 25

• 25.5

What is the most appropriate measure of central tendency for the following data set, and why?

21 23 23 23 24 25 26 27 29 30 38 44 82 110

• The mode, because it is easy to calculate

• The mean, because it is the best measure of central tendency

• The mean, because it is an unbiased statistic

• The median, because the data set is negatively skewed

• The median, because the data set is positively skewed

The tutors decide to all grade the same assignment, chosen at random. If they all give it a similar grade, we can say that the marking criteria has good:

• test-retest reliability

• inter-rater reliability

• predictive validity

• face validity

• causal interpretability