Ch.4

Question 1

What falls under qualitative data? (3)

Answer 1

• absolute numbers
• percentages
• proportions

Question 2

What falls under quantitative data? (3)

Answer 2

• summary measures of location
• summary locations of spread
• summary measures of position

Question 3

What are summary measures of location? (3)

Answer 3

• mean
• median
• mode

Question 4

What are summary measures of spread? (4)

Answer 4

• Range
• Variance
• standard deviation
• coefficient of variation

Question 5

What are summary measures of position? (2)

Answer 5

• Percentiles

- Quartiles

Question 6

Define summary measures of location:

Answer 6

summarizes information and indicates which numbers tend to aggregate the values of the variable

-tendency for the values of a random variable to cluster round its mean, mode, or median.

Question 7

What is another name for summary measures of location?

Answer 7

central tendency measures

Question 8

Mean of a population is represented by what character?

Answer 8

μ

Question 9

What is the median?

Answer 9

middle value

Question 10

What is it called when there are two modes?

Answer 10

bimodal distribution

Question 11

What is the spread/variability?

Answer 11

Measures of dispersion.
Variability = indicators
of the homogeneity of the values

• more distant from mean = data is more dispersed
• higher value of dispertion = greater variability = less homogenous

Question 12

What is range?

Answer 12

difference between upper and lower value

Question 13

What is average deviation?

Answer 13

measures variability of data around the mean/avg distance to the mean
-add all the distances of each observation to the mean divided by number of observations

Question 14

When do you use variance versus sample variance?

Answer 14

sample is a sample of the population

Variance is total population

Question 15

The units of standard deviation are the same or different than the variable?

Answer 15

same

Question 16

What is the coefficient of variation?

Answer 16

percentage of the mean that the standard deviation represents

Question 17

Why is coefficient of variation useful?

Answer 17

-allows comparison of mean and variance of variables measured in different units to see which varies more

Question 18

Define the summary measures of position

Answer 18

indicate which place or position a certain value of the variable occupies within the set of observed values

-divide set of observations into equal parts

Question 19

What is a percentile?

Answer 19

indicate the
percentage of values that are equal to or
lower than the value we have measured

ex. height of 130 cm being in the
percentile 60, it means…that 60% of children of that age in this
population measure equal to or less

Question 20

When do we use percentiles?

Answer 20

to standardize anthropometric measurements ex. weight and height

Question 21

Define Chebyshev’s inequality

Answer 21

regardless of how data are
distributed, at least 75% of the values of the variable
are included in [μ±2 SD]

ex. If the mean is 34 and the standard deviation is 2, at
least 75% of the values are between 34-4 and 34+4, this is
between 30 and 38

Question 22

What happens if the mean and medial are equal?

Answer 22

the

distribution is symmetrical

Question 23

When do we use range?

Answer 23

when we should

emphasize the extreme values

Question 24

What graphs do we use for qualitative variables? what else do we use these for? (2)

Answer 24

• Bar chart
• Pie chart
• also quantitative discrete variables

Question 25

What graphs do we use for quantitative continous variables? (2)

Answer 25

• histograms

- frequency polygons

Question 26

What do we use a histogram for?

Answer 26

frequency of the values displayed by using bars of different heights

Question 27

How does a histogram differ from a bar chart?

Answer 27

histogram groups values into ranges

Question 28

What do we use a frequency polygon for?

Answer 28

• understand shape of variable distribution

- useful to visualize frequency changes