Descriptive Statistics

Question 1

Nominal

Answer 1

exhaustive and mutually exclusive categoies

categorical

Question 2

ordinal

Answer 2

ordered

categorical

Question 3

interval

Answer 3

equal distances between scores
calculate differences but not proportions
(discrete or continuous)

Question 4

Ratio

Answer 4

interval + a true zero
percent correct, 50% is twice as accurate 25%
(discrete or continuous)

Question 5

mean

Answer 5

interval, ratio

central tendency

Question 6

median

Answer 6

ordinal, interval, ratio

central tendency

Question 7

mode

Answer 7

all types 
(central tendency)

Question 8

min, max, range, interquartile range

Answer 8

measures of variability

Question 9

standard deviation

Answer 9

dispersion of scores around the mean

Question 10

standard error of the mean

Answer 10

How far is the sample mean likely to be from the population mean?

Question 11

visualization of data

Answer 11

pie chart, scattor plot, bar graph, line graph

Question 12

normal distribuation

Answer 12

“gaussian curve”
largest number of observations at the center
2/3 of observations will fall within 1 SD of mean

Question 13

skewed

Answer 13

more extreme scores in one direction

negatively skewed more scores towards right

named by tail side

Question 14

kurtosis

Answer 14

peakedness and shape of tails

Question 15

z score

Answer 15

how many SD above or below the mean

relate normal distribution to other z scores

Question 16

t distrubuation

Answer 16

shift and scaled so that m = 50 and sd =10

this is used for small sample sizes and unknown population standard dev

Question 17

outliers

Answer 17

set a criteria a priori based on meausres and literature
trimming of reaion times is common. - like more than 2.5 SD lower than mean.

NEVER remove data without minially describing