Unit 2

Question 1

what are the three representative values for a data set

Answer 1

mean
median
mode

Question 2

what is the mean and how do you calculate it

Answer 2

arithmetic average
add up the scores and divide by the total number of scores

Question 3

what is the median

Answer 3

the middle number of the data set

Question 4

what is the mode

Answer 4

most frequent or most common value in the distribution

Question 5

when using nominal variables what is the only relevant representative value

Answer 5

mode

Question 6

if you have a normal distribution what does that mean for the mean, median and mode

Answer 6

they will all be the same

Question 7

if you have a skewed distribution what does that mean for the mean, median and mode

Answer 7

that they will all be different

Question 8

if a distribution is heavily skewed what measures of central tendency are the most useful in determingin what is going on

Answer 8

mode and median as these values are less affected by extremes

Question 9

what happens with the mean and median in a positively skewed distribution

Answer 9

mean > median

Question 10

what happens with the mean and median in a negatively skewed distribution

Answer 10

mean < median

Question 11

what does variability refer to

Answer 11

how spread out the values are

Question 12

what are the three measures of variability

Answer 12

range
variance
standard deviation

Question 13

what does range refer to? how is it calculated

Answer 13

simplest measure of variability
subtract lowest number from highest number in your data set

Question 14

what is variance

Answer 14

measure of how close or spread out the scores are around the mean
it is the average mathematical distance each score in the data set is from the mean

Question 15

what is standard deviation

Answer 15

the square root of the variance
it measures the variation in the same units as the original values

Question 16

what is a Z score

Answer 16

standardized score that tells us the number of standard deviations a score is above or below the mean of a distribution

Question 17

what are the two things you require to calculate a Z score

Answer 17

mean and standard deviation

Question 18

what do representative values tell us

Answer 18

they help us make sense of data and interpret in a more meaningful way

Question 19

are some measures of representative values better than others? When? Why?

Answer 19

standard deviation is better than variance as it gives us an answer back in the same units as the original data
Z scores are more useful than standard deviation as we can use them to compare data from different data sets

Question 20

how do you calculate the median

Answer 20

(N+1)/2

Question 21

what measure of central tendency is most affected by outliers

Answer 21

mean

Question 22

what kind of skew is created by a ceiling effect

Answer 22

left sided skew

Question 23

what kind of skew is created by a floor effect

Answer 23

right sided skew