Chap I

Question 1

Individuals

Answer 1

The objects described by a set of data - can be people, animals, or things

Question 2

Variable

Answer 2

Any characteristic of an individual - can take different values for different individuals

Question 3

Categorical Variable

Answer 3

places in individual into one of several groups or categories - values are names or labels

Question 4

Quantitative Variable

Answer 4

takes numerical values for which it makes sense to find an average - represent a measurable quality

Question 5

Discrete Variables

Answer 5

A variable that cannot take on any value between its minimum and maximum value - for example, when flipping a coin, the number of heads can be any integer value between 0 and plus infinity, but could not be any value because you could not get 2.5 heads.

Question 6

Continuous Variable

Answer 6

A variable that can take on any value between its minimum and maximum value - for example, the weight of a firefighter between 150-250 pounds, because the firefighter’s weight could be any value between 150-250 pounds.

Question 7

Univariate Data

Answer 7

A study that looks at only one variable - e.g. a study that looks at the weight of high school students

Question 8

Bivariate Data

Answer 8

A study that examines the relationship between two variables - e.g. a study looking at the relationship between the height and weight of high school students.

Question 9

Population

Answer 9

The total set of observations that can be made

Question 10

Sample

Answer 10

A set of observations drawn from a population

Question 11

Census

Answer 11

A study that obtains data from every member of a population - often no practical because of time/cost involved.

Question 12

Distribution

Answer 12

Tell us what values the variable takes and how often it takes those values

Question 13

Inference

Answer 13

Drawing conclusions that go beyond the data at hand, though it depends on how the data is produced

Question 14

Frequency Table

Answer 14

Displays counts (frequencies) of x variable in each category

Question 15

Relative Frequency Table

Answer 15

Displays percentages (relative frequencies) of x variable in each category

Question 16

Interquartile Range (IQR)

Answer 16

Measures of the range of the middle 50% of the data - measure of variability, equal to Q3 - Q1.

Question 17

Five-Number Summary

Answer 17

Consists of the smallest observation, the first quartile, the median, the third quartile, and the largest observation & divides each distribution roughly into quarters.

Question 18

Boxplot

Answer 18

A type of graph used to display patterns of quantitative data & splits the data into quartiles, consisting of a box the size of the Q1 & Q3, with a line in the middle representing the median and lines, or whiskers, extending from the box to the largest and smallest observations that aren’t outliers.

Question 19

Standard Deviation

Answer 19

A numerical value used to indicate how widely individuals in a group vary - measures the deviation from the mean and differs based upon population or a sample. Standard deviation for a population is found using σ = sqrt [ Σ ( Xi - X )2 / N ] and standard deviation for a sample is found using s = sqrt [ Σ ( xi - x )2 / ( n - 1 ) ]

Question 20

Variance

Answer 20

A numerical value used to indicate how widely objects in a group vary and is equal to the square of standard deviation. Variance of a population is found using σ2 = Σ ( Xi - X )2 / N & variance of a sample is found using s2 = Σ ( xi - x )2 / ( n - 1 )

Question 21

Roundoff Error

Answer 21

When the exact percentages add up to 100%, but the rounded percentages only come close - does not indicate mistakes in work

Question 22

Pie Chart

Answer 22

Shows distribution of categorical variable as a pie, with slices sized by count or percentage per category - must have all categories

Question 23

Bar chart

Answer 23

Represent each category as a bar, where heights show the count or percentage - can be more flexible than a pie chart and display the distribution of categorical variables or compare quartiles.

Question 24

Two-Way Table

Answer 24

Examines relationships between categorical variables - contains a row variable and a column variable

Question 25

Marginal Distribution

Answer 25

The distribution of values of one of the categorical variables in a two-way table of counts among all individuals described by the table, though a percentage is often more informative. Divide the row/column total by the table total and convert to a percentage to get the MD.

Question 26

Conditional Distribution

Answer 26

Describes values of that variable among individuals who have a specific value of another variable - separate conditional distribution for each value of the other variable, often uses relative frequencies

Question 27

Segmented Bar Graph

Answer 27

A bar graph that uses one category to separate into bars (ex: male/female) and another divided into connected segments of the bar, adding up to 100%.

Question 28

Side-by-Side Bar Graph

Answer 28

A bar graph where two categories (ex: male/female) are made of two (or more) separate bars for one category, the bars being repeated each category

Question 29

Association

Answer 29

When knowing the value of a variable helps to predict the value of the other

Question 30

Simpson's Paradox

Answer 30

An effect where the marginal association between two categorical variables is qualitatively different than the partial association between the same two variables - tldr - averages can be misleading

Question 31

Dotplot

Answer 31

A plot where each data value is shown as a dot above its locative on a numberline.

Question 32

Shape

Answer 32

Describes the way a graph looks - focus on the main features, such as major peaks, clusters, obvious gaps, and potential outliers

Question 33

Mode

Answer 33

the most common value

Question 34

Center

Answer 34

the midpoint of the data

Question 35

Spread

Answer 35

similar to range, but not a singular value - data varies from __ to __

Question 36

Range

Answer 36

A measure of variability that shows the full spread of the data - single value gotten by subtracting the smallest value from the largest value

Question 37

Outlier

Answer 37

Any observation that falls more than 1.5 x IQR above the third quartile or below the first quartile

Question 38

Symmetric Distribution

Answer 38

When the right and left sides of a graph are approximately mirror images of the other

Question 39

Skewed Right

Answer 39

When the right side of the graph is longer than the left - in the direction of the tail

Question 40

Skewed Left

Answer 40

When the left side of the graph is longer than the right - in the direction of the tail

Question 41

Unimodal

Answer 41

having a single peak

Question 42

Bimodal

Answer 42

having two clear peaks

Question 43

Multimodal

Answer 43

having more than two clear peaks

Question 44

Stemplot

Answer 44

A plot used to display quantitative data, usually from smaller data sets, consisting of a stem (including all but the final digits of an observation) and leaves (the final digit of an observation

Question 45

Splitting Stems

Answer 45

Dividing a stem into further pieces - eg 0-9 stem becomes two 0 stems, one with a spread of 0-4 and the other with a spread of 5-9

Question 46

Back-to-Back Stem

Answer 46

A stemplot plot where leaves are on either side of the stem, often to represent two different categories of data

Question 47

Plots

Answer 47

A graphing technique used to represent a data set, often showing the relationship between or more variables

Question 48

Histogram

Answer 48

A graph of distribution using quantitative data where nearby values are grouped together

Question 49

Mean

Answer 49

An average score that shows how large each data value would be if the total were split equally amongst the observations & found by finding the sum of individual scores and diving it by the number of individuals. Not resistant measure of center.

Question 50

Median

Answer 50

The midpoint of distribution, where around half of the observations are smaller than the value and about half are larger. Resistant measure of center.