Descriptive Statistics

Question 1

mean

Answer 1

average of a set of measurements

Question 2

what is the most common metric to describe LOCATIONN of a frequency distribution

Answer 2

mean

Question 3

sample mean

Answer 3

average of the measurements in the sample

Question 4

how to calculate the sample mean

Answer 4

sum of all the observations divided by the number of observations

Question 5

standard deviation (s)

Answer 5

measures how far from the mean the observations typically are

Question 6

most used measurement of distribution spread

Answer 6

standard deviation

Question 7

what does a large vs small standard deviation indicate about the data

Answer 7

large = most of the observations are far from the mean

small = most observations are close to the mean

Question 8

how to calculate the standard deviation

Answer 8

the square root of the variance

Question 9

can the standard deviation be negative

Answer 9

NO

Question 10

variance (s2) formula

Answer 10

Question 11

what is the deviation

Answer 11

difference between a measurement and the mean

Question 12

what will the average of the deviations be

Answer 12

zero

Question 13

how to find the variance

Answer 13

square the deviations

Question 14

how is the standard deviation often expressed

Answer 14

relative to the mean

Question 15

coefficient of variation (CV)

Answer 15

calculates the standard deviation as a percentage of the mean

Question 16

higher vs lower coefficient of variation

Answer 16

higher = more variability relative to the mean

lower = individuals are more consistently the same relative to the mean

Question 17

when does the coefficient of variation only make sense

Answer 17

when all measurements are greater than or equal to zero

Question 18

formula for coefficient of variation

Answer 18

divided the standard deviation by the sample mean

Question 19

what is the sample size in a frequency table

Answer 19

the frequency total NOT the number of rows (this total is 395)

Question 20

median

Answer 20

middle observation in a set of data

Question 21

how is the median often displayed

Answer 21

a box plot

Question 22

how to calculate the median

Answer 22

sort the sample observations from smallest to largest

(odd number of observations = middle number)

(even number of observations = average of middle pair)

Question 23

quartiles

Answer 23

values that partition data into quarters

Question 24

what is the first, second and third quartiles

Answer 24

first: Middle value of the measurement below the median

second: the median

third: Middle value of the measurements LARGER than the median

Question 25

interquartile range (IQR)

Answer 25

Span of the middle half of the data from the first quartile to the third quartile

Question 26

how to calculate the IQR

Answer 26

Compute the first and third quartiles Then subtract them

Question 27

Box plots display

Answer 27

the median and interquartile range

Question 28

what do the lower and upper edges of a box plot represent

Answer 28

first and third quartiles

Question 29

what is the interquartile range in a box plot

Answer 29

the span of the box

Question 30

what is the horizontal line dividing a box in box plot

Answer 30

the median

Question 31

how are extreme values shown in a box plot

Answer 31

by a dot or line

Question 32

what are examples of measures of spread

Answer 32

standard deviation interquartile range

Question 33

what are examples of measures of location

Answer 33

mean and median

Question 34

when are the mean and standard deviation LESS informative than the median and interquartile range

Answer 34

data is strongly skewed or have extreme observations

Question 35

when data is strongly skewed or have extreme observations what measures are LESS informative

Answer 35

mean and standard deviation

Question 36

median vs mean

Answer 36

median is the middle measurement of a distribution BUT the mean is the center of gravity

Question 37

is the mean sensitive to extreme values

Answer 37

YES

Question 38

is the median sensitive to extreme values

Answer 38

Less so than the mean

Question 39

is the standard deviation sensitive to extreme values

Answer 39

YES

Question 40

is the interquartile range affected by extreme values

Answer 40

NO

Question 41

percentile vs quantiles

Answer 41

percentile - value below which the X percent of the individuals lie (50th percentile = median = half the data OR 25th percentile = first quartile) quantiles - proportion less than or equal to the given value (represented by decimal) (10th percentile = 0.10 quartile Median = 0.5 quartile)

Question 42

most used descriptive stats for a categorical variable

Answer 42

proportions

Question 43

what is the analogues statement for the mean, standard deviation, median and interquartile range

Answer 43

mean : Standard deviation :: median : interquartile range

Question 44

how is the Coefficient of variation beneficial in comparisons

Answer 44

allows us to compare variables with different units because the CV is unitless

Question 45

how are measures of mean and median similar

Answer 45

both describe location of frequency distribution

Question 46

what is the purpose of the median

Answer 46

to partition ordered measures into two halves

Question 47

are the mean, median, st.d and IQR similar or different when the distribution is symmetrical and unimodal

Answer 47

give similar information

Question 48

what parameter gives the bulk of information when data is skewed

Answer 48

the median because the mean is pulled towards the outliers and away from the bulk of data

Question 49

is standard deviation more or less sensitive to extreme values than the mean

Answer 49

MORE sensitive

Question 50

why is the st.d more sensitive to extreme values than the mean

Answer 50

because extreme values of large deviations which when squared amplify that effect

Question 51

when is IQR better for data and when is the STDEV

Answer 51

IQR - regarding the MAIN part of the data STDEV - better for information of ALL data in the distribution (with the spread)

Question 52

how do you calculate a proportion

Answer 52

number of category divided by total number in all categories

Question 53

what does the proportion (P-hat) estimate

Answer 53

estimate of true population proportion (p)

Question 54

what must the proportion sum to

Answer 54

1