Chapter 2

Question 1

Data

Answer 1

values of a variable

Question 2

What are the 2 types of data?

Answer 2

qualitative and quantitative

Question 3

What are the 2 types of quantitative data?

Answer 3

discrete

continuous

Question 4

Time series data

Answer 4

ordered data values observed over time

Question 5

Cross section data

Answer 5

data values observed at a fixed point in time

Question 6

Classes

Answer 6

categories used for grouping data

Question 7

Frequency

Answer 7

the number of observations that fall in a class

Question 8

Frequency distribution

Answer 8

a listing of all classes and their frequencies

Question 9

Relative frequency

Answer 9

the ratio of the frequency of a class to the total number of observations

Question 10

Relative-frequency distribution

Answer 10

a listing of all classes and their relative frequencies

Question 11

Lower cutpoint

Answer 11

the smallest value that could go in a class

Question 12

Upper cutpoint

Answer 12

the smallest value that could go in the next higher class (equivalent to the lower cutpoint of the next higher class)

Question 13

Midpoint

Answer 13

the middle of a class, found by averaging its cutpoints

Question 14

Width

Answer 14

the difference between the cutpoints of a class

Question 15

What is a frequency distribution?

Answer 15

a list or table containing the values of a variable (or set of ranges within which the data fall) and the corresponding frequencies with which each value occurs (or frequencies with which data fall within each range)

Question 16

Why do we use frequency distributions?

Answer 16

it summarizes data by condensing the raw data in a more useful form and allows for a quick visual interpretation of the data

Question 17

Discrete data

Answer 17

possible values are countable

Question 18

Continuous data

Answer 18

may take on any value in some interval

Question 19

What kind of data uses bar and pie charts?

Answer 19

qualitative (category) data

Question 20

Why is it useful to use a stem and leaf diagram?

Answer 20

it is a simple way to see distribution details from qualitative data

Question 21

Line charts are used to show…

Answer 21

the values of one variable vs TIME

Question 22

Scatter diagrams shows points for…

Answer 22

bivariate data

- one value measured on the vertical axis and the other measured on the horizontal axis

Question 23

Mean

Answer 23

the arithmetic average of data values

- sum of the values divided by the number of values

Question 24

Median

Answer 24

in an ordered array, it is the “middle” number that splits the distribution in half

Question 25

Is the median affected by extreme values? Mode?

Answer 25

NO, NO

Question 26

Mode

Answer 26

a measure of location
the value that occurs most often
used for numerical or categorical data
there may be no mode or there may be serval modes

Question 27

Distribution of a data set

Answer 27

a table, graph, or formula that provides the values of the observations and how often they occur

Question 28

Which measure of location is the “best”?

Answer 28

Usually the mean unless there are extreme values (outliers) then the median is used

Question 29

What does (n) represent? What about (N)?

Answer 29

sample

population

Question 30

What do you do first if you see there is an outlier?

Answer 30

check for human error

Question 31

Variation

Answer 31

gives information on the spread or variability of the data values

Question 32

Range

Answer 32

simplest measure of variation

difference between the largest and smallest observations

Question 33

What are some disadvantages of the range?

Answer 33

it ignores the way in which data are distributed

it’s sensitive to outliers

Question 34

What are the benefits of the interquartile range? Equation?

Answer 34

it can eliminate the outlier problems

IQR = 3rd - 1st

Question 35

Degrees of freedom

Answer 35

the number of observations that are free to vary after sample mean has been calculated

Question 36

What is the most commonly used measure of variation?

Answer 36

Standard deviation

Question 37

What must the sum of deviations equal?

Answer 37

0!!!!

Question 38

Coefficient of variation

Answer 38

measures relative variation

always in percentage