Module 2: Summarizing Data

Question 1

scatterplots

Answer 1

-useful for visualizing the relationship between 2 numerical variables
-each point is a single case

Question 2

dot plots

Answer 2

useful for visualizing one numerical variable

Question 3

what is one way to measure the centre of a distribution of data?

Answer 3

the mean (average)

Question 4

sample statistic

Answer 4

point estimate of the population mean

Question 5

histograms

Answer 5

-view of data density
-convenient for describing the shape of the data distribution

Question 6

what do higher bars on histograms represent?

Answer 6

where the data are relatively more common

Question 7

4 types of modality

Answer 7

unimodal, bimodal, multimodal, and uniform

Question 8

3 types of skewness

Answer 8

right skewed, left skewed, or symmetric

Question 9

2 measures of variability

Answer 9

variance and standard deviation

Question 10

deviation

Answer 10

distance of an observation from the mean

Question 11

variance

Answer 11

-average squared deviation from the mean
-tells you the amount of spread in the data

Question 12

standard deviation

Answer 12

-square root of the variance and has the same units as the data
-useful for considering how far data are distributed around the mean

Question 13

box plot

Answer 13

summarizes a data set using 5 statistics while also plotting unusual observations

Question 14

5 statistics (plus 1 optional one) used for box plots

Answer 14

upper whisker, Q3, median, Q1, lower whisker, mean (optional)

Question 15

median

Answer 15

value that splits the data in half when ordered in ascending order

Question 16

what is the median when there are an even number of observations?

Answer 16

the average of the 2 values in the middle

Question 17

25th percentile =

Answer 17

first quartile Q1

Question 18

50th percentile=

Answer 18

median

Question 19

75th percentile=

Answer 19

third quartile Q3

Question 20

outlier

Answer 20

-observation beyond the max reach of the whiskers
-appears extreme relative to the rest of the data

Question 20

interquartile range, IQR

Answer 20

range between Q3 and Q1

Question 20

whiskers

Answer 20

-capture data outside of the IQR box

Question 20

T or F: median and IQR are more robust to skewness and outliers than mean and SD

Answer 20

true

Question 20

is distribution is skewed or has extreme outliers, centre is often defined as _________

Answer 20

the median

Question 20

if distribution is symmetric, centre is often defined as _______

Answer 20

the mean

Question 21

contingency table

Answer 21

summarizes data for 2 categorical variables

Question 21

name 2 plots that combine numerical and categorial data to compare numerical data across groups

Answer 21

side-by-side plots and multiple histograms

Question 21

bar plot

Answer 21

displays a single categorical variable

Question 22

relative frequency bar plot

Answer 22

bar plot where there are proportions instead of frequencies

Question 23

stacked bar plot

Answer 23

graphical display of contingency table info for counts

Question 24

side-by-side bar plot

Answer 24

same info as stacked bar plot but has info beside each other instead of on top

Question 25

frequency

Answer 25

shows the count in each category
*difficult to interpret if groups have unequal numbers

Question 26

row proportion

Answer 26

shows the proportion of the row total
*easier to compare between rows

Question 27

column proportion

Answer 27

useful to show proportion of explanatory variable