PSYC1040 Z scores

In a rectangular distribution, a z-score of 0 would be equivalent to the:

• 1st percentile

• 16th percentile

• 50th percentile

• 84th percentile

• 98th percentile

For a normal distribution with a mean of 40 and a standard deviation of 10, what is the approximate value of the 95th percentile:

• 50

• 56

• 60

• 64

• 80

When raw scores are transformed into z-scores, then the z-scores

• are normally distributed

• maintain the same mean and SD as the raw scores

• have no values below zero

• have the same shaped distribution as the raw scores

• will add up to 1

Which of the following is not true of a normal distribution?

• It is symmetrical about its mean

• The tails approach the x-axis asymptotically

• There is only a small percentage of scores in the tails of the distributions

• There is always 68.26% of the scores between z=-1 and z=1

• The SD of the scores is always the same

In a positively skewed distribution, the sum of the Z-scores would be:

• zero

• greater than zero

• less than zero

• 1

• -1

In a normal distribution, the percentage of scores between the mean and a score one standard deviation above the mean

• depends upon the value of the SD

• is always a fixed percentage

• depends upon the mean

• depends upon the interquartile range

• depends upon the shape of the distribution

Which of the following does not apply to all distributions after conversion from raw scores to Z-scores?

• They always have a mean of 0

• They always have a standard deviation of 1

• They always have a variance of 1

• They are always normal

• They have a variance of 1 and they are always normal