Unit 1

Question 1

Descriptive Division

Answer 1

Numbers that summarize and describe data sets

Question 2

Inferential Division

Answer 2

Uses a sample set to draw inferences about a larger population

Question 3

Random Sample

Answer 3

Every member has an equal opportunity to be selected

• Because of chance factors, the sample will differ from the total makeup of the population

Question 4

Stratified Random Sampling

Answer 4

Population is divided into a number of subgroups, called a strata, where random samples are then taken from.

Question 5

Representative Sample

Answer 5

Sample chosen to match the qualities of the population from which it is drawn

Question 6

Biased Sampling

Answer 6

A sampling method is biased if each element does not have an equal chance of being selected

Question 7

Independent Variable

Answer 7

The variable manipulated by the experimenter

Question 8

Variable Levels

Answer 8

Number of different independent variables within the study

Question 9

Dependent Variable

Answer 9

Fixed variable that measures the experimental outcome

Question 10

Qualitative (categorical) Variable

Answer 10

Variables with no natural sense of order. Data is not numerical and fits into categories.

• Hair color, names, shirt color.

Question 11

Quantitative (numerical) Variable

Answer 11

Variables measured on a numerical scale

• persons age, shoe size, speed traveled

Question 12

Discreet Variable

Answer 12

Variables that can only take on a finite number of values

• SAT/ACT scores, persons age, current temp

Question 13

Continuous Variable

Answer 13

Variables that can take on any number of values in a certain range

Question 14

Nominal Scale

Answer 14

Nominal variables are used to “name,” or label a series of values

• no reasoning/significance behind which category appears firs. Simply categorizes the responses

Question 15

Ordinal Scale

Answer 15

An order scale in which the numbers are assigned to the objects to determine the relative extent to which the dependent variable is possessed.

• no way to determine the equivalence between responses, so it is the order in which they appear that matters but not the degree of difference between the responses
• consumer satisfaction of a product they purchased

Question 16

Interval Scale

Answer 16

Objects are orderd

The difference between the two variables is meaningful and equal

The presence of zero is arbitrary. - does not have a true “zero” point

• not all ratios are even comparisons

Question 17

Ratio Scale

Answer 17

Objects are ordered

The same difference between any two points has the same meaning

The ratio between two points has the same meaning

It has a true “zero” point.

Question 18

Positive Skew Distribution

Answer 18

Distribution trail carries to the right

Question 19

Negative Skew Distribution

Answer 19

Distribution trail carries to the left

Question 20

Binomial Distribution

Answer 20

Distribution with two distinct peaks

Question 21

Leptokurtic (L)

Answer 21

Long tails relative to “normal” distribution

Question 22

Platykurtic

Answer 22

Short tails relative to “normal” distribution

Question 23

Symmetric Distribution

Answer 23

Tails extend equally in both direction

Question 24

Surges Rule

Answer 24

Used for calculating total class intervals

1 + Log2(N) where N = number of observations

Question 25

Rice Rule

Answer 25

Used for calculating total class intervals

2 X cubed root of total observations

Question 26

Class (Class Intervals)

Answer 26

Division of data into bin width

Question 27

Class Frequency

Answer 27

Number of observations in the class of data

Question 28

Bin Width Rules

Answer 28

Surges Rule = 1+Log2(n)

Rice Rule = 2 x cube root N

N = total number of observations

Question 29

Center Distribution - Balance Scale

Answer 29

Point at which distribution is even

Question 30

Center Distribution - Smallest Absolute Deviation

Answer 30

Absolute Deviation = sum of the difference in values from deviation

Center Distribution - smallest number for which the sum of the absolute deviations is smallest

Question 31

Center Distribution - Smallest Squared Deviation

Answer 31

Squared Deviation = difference in values from deviation squared

Center Distribution - smallest number for which the sum is smallest

Question 32

Three Ways to Define a Central Tendency

Answer 32

1. Point at which distribution is balanced
2. Number which minimizes the sum of the absolute differences
3. Number which minimizes the sum of the squared differences

Question 33

Mode

Answer 33

Most frequently occurring value

Question 34

Mean

Answer 34

Total value / Total numbers

• Minimizes the sum of squared deviations
• Where we hope a distribution is balanced

Question 35

Median

Answer 35

Midpoint of a distribution ranked from lowest to highest

• Minimizes the sum of absolute deviations

Question 36

Range

Answer 36

Highest value - Lowest value

Question 37

Interquartile Range (IQR)

H-Spread

Answer 37

Range of the middle 50% of the values

IQR = 75th percentile - 25th percentile

Question 38

Semi-Interquartile Range

Answer 38

Interquartile range divided by 2

The median plus or minus the semi-interquartile will contain 50% of the values

Question 39

Variance

Answer 39

The expectation of the squared deviation of a random variable from its mean.

Informally, it measures how far a set of numbers are spread out from their average value

Question 40

Standard Deviation

Answer 40

Square root of the variance

Variance - average squared difference of the values from the mean