Chapter 2

Question 1

Data

Answer 1

The facts and figures collected, analyzed, and summarized for presentation and interpretation.

Question 2

Variable

Answer 2

A characteristic or quantity of interest that can take on different values.

Question 3

Observation

Answer 3

Set of values corresponding to a set of variables.

Question 4

Variation

Answer 4

The difference in a variable measured over observations.

Question 5

Random variable/uncertain variable

Answer 5

A quantity whose values are not known with certainty.

Question 6

Population

Answer 6

All elements of interest

Question 7

Sample

Answer 7

Subset of population

Question 8

Random sampling

Answer 8

A sampling method to gather a representative sample of the population data.

Question 9

Quantitative data

Answer 9

Data on which numeric and arithmetic operations such as addition subtraction multiplication and division can be performed.

Question 10

Categorical data

Answer 10

Data on which arithmetic operations cannot be performed.

Question 11

Cross sectional data

Answer 11

Data collected from several entities at the same or approximately the same point in time.

Question 12

Time series data

Answer 12

Data collected over several time periods.

Ex) sale reports

Question 13

Graphs of time series data are frequently found where?

Answer 13

In business and economic publications

Question 14

Time series data help analysts understand what?

Answer 14

What happened in the past, identify trends over time and project future levels for the time series.

Question 15

Experimental study

Answer 15

A variable of interest is first identified.

Then one or more other variables are identified and controlled or manipulated so that data can be obtained about how they influence the variable of interest.

Question 16

Non experimental study or observational study

Answer 16

Make no attempt to control the variables of interest.

Question 17

What is the most common type of observational study?

Answer 17

A survey

Question 18

Frequency distribution

Answer 18

A summary for data that shows the number (frequency) of observations in each of several non overlapping classes, typically referred to as bins, when dealing with distributions.

Question 19

Relative frequency distribution

Answer 19

It’s a tabular summary of data showing the relative frequency of the data for each bin

Question 20

Percent frequency distribution

Answer 20

Summarizes the percent frequency of the data for each bin.

Question 21

Three steps necessary to define the classes for a frequency distribution with quantitative data:

Answer 21

1. Determine the number of non overlapping bins
2. Determine the width of each bin.
   - look at the range
3. Determine the bin limits

Question 22

Histogram

Answer 22

A common graphical presentation of quantitative data.

Question 23

How is the histogram constructed?

Answer 23

By placing the variable of interest on the horizontal axis and the selected frequency measure (absolute, relative, percent frequency) on the vertical axis.

Question 24

How is the frequency measure of each class shown in histogram?

Answer 24

By drawing a rectangle whose base is determined by class limits on the horizontal axis and whose height is the corresponding frequency measure.

Question 25

What does histogram provide information on?

Answer 25

Shape, or form of a distribution .

Question 26

Skewness

Answer 26

Lack of symmetry .

Question 27

What is an important characteristic of the shape of the distribution?

Answer 27

Skewness

Question 28

Cumulative frequency distribution

Answer 28

A variation of the frequency distribution that provides another tabular summary of quantitative data.

Question 29

Mean

Answer 29

Is the average.

Question 30

Median

Answer 30

Value in the middle when the data are arranged in ascending order.

Question 31

Mode

Answer 31

Value that occurs most frequently in the data set.

Question 32

Geometric mean

Answer 32

Nth root of the product of n values.

Question 33

Range

Answer 33

Minimum - maximum

Question 34

Variance

Answer 34

Measure of variability that utilizes all data.

Question 35

Variance is based on?

Answer 35

The deviation about the mean, which is the difference between the values of each observation and the mean.

Question 36

The deviations about the mean are squared while computing what?

Answer 36

Variance

Question 37

Standard deviation

Answer 37

Positive square root of the variance

Question 38

Coefficient of variation

Answer 38

Measures the standard deviation relative to the mean.

Question 39

Coefficient of variation is expressed as what ?

Answer 39

Percentage

Question 40

Percentile

Answer 40

Value of a variable at which a specified (approximate) percentage of observations are below that value.

Question 41

The pth percentile tells us the point in the data where:

Answer 41

• approximately p percent of the observations have the values less than the pth percentile.
• approximately (100 - p) percent of the observations have values greater than pth percentile.

Question 42

Quartiles

Answer 42

When the data is divided into four equal parts:

• each part contains approximately 25% of the observations
• division points are referred to as quartiles.

Question 43

Q1 is?

Answer 43

25th percentile

Question 44

Q2 ?

Answer 44

50th percentile

Question 45

Q3

Answer 45

75 percentile

Question 46

Z score

Answer 46

Measures the relative location of a value in the data set.

Question 47

Z score helps determine what?

Answer 47

How far a particular value is from the mean relative to the data sets standard deviation.

Question 48

Empirical rule

For data having a bell shaped distribution

Answer 48

• within 1 std dev. - approximately 68% of data values.
• within 2 std. Dev. - approximately 95% of the data values.
• within 3 std dev. - almost all the data values.

Question 49

Outliers

Answer 49

Extreme values in a data set.

Question 50

Outliers can be identified using

Answer 50

Standardized values (z scores)

Question 51

Any data value with a z score less than _____ or greater than ____ is an outlier.

Answer 51

-3 or +3

Question 52

Box plot

Answer 52

Graphical summary of the distribution of data.

Question 53

How are box plots developed?

Answer 53

From the quartiles for a data set.

Question 54

Scatter charts

Answer 54

Useful graph for analyzing the relationship between two variables.

Question 55

Covariance

Answer 55

Descriptive measure of the linear association between 2 variables.

Question 56

Correlation coefficient

Answer 56

Measures the relationship between two variables