Descriptive statistics
o :## describe a sample
Inferential statistics
o :## make inferences about a population from a sample
What are the three measures of central tendency?
o :## mean, median, and mode
When is the mean not the best measure of central tendency?
o :## when there are outliers;...
RPE exam Questions and Answers
Descriptive statistics
o :## describe a sample
Inferential statistics
o :## make inferences about a population from a sample
What are the three measures of central tendency?
o :## mean, median, and mode
When is the mean not the best measure of central tendency?
o :## when there are outliers; they will skew the mean
When is the mode the most useful measure of central tendency?
o :## when describing frequency data
Range
o :## the distance between the lowest and highest scores (taking into account the
upper and lower real limits)
Standard deviation
, 2024/2025 2|Page
o :## How far a score falls from the mean on average; the square root of variance
If a graph shows a sample with a tail to the right, it is:
o :## positively skewed
If a graph shows a sample with a tail to the left, it is:
o :## negatively skewed
What are Z-scores and why do we use them?
o :## Z-scores convert any singular score into the number of SDs it is away from
the mean. We use them because they are standardized, which means we can
compare different sample means regardless of scale.
What is the Z-score formula and what are features of a Z-score distribution on a graph?
o :## Z = X-M/SD, on a Z-score graph the mean = 0 and SD = 1
What are the four scales of measurement?
o :## nominal, ordinal, interval, and ratio
Nominal data
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o :## describes categories (i.e., major, religion), always use mode as central
tendency
Ordinal data
o :## rank order, we know that one value is better than another, but we don't
know how much better (i.e., first and second place), uses mode or median as
central tendency
Interval data
o :## has equal intervals but does not have a true zero (i.e., degrees farenheit)
Ratio data
o :## has equal intervals and a true zero
Independent variable (IV)
o :## the manipulated variable
Dependent variable (DV)
o :## the outcome measurement
Discrete DV
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