Week 3: Descriptive Analysis Of Numerical Data

Question 1

Descriptive analysis of numerical data

Answer 1

1) Frequency distributions
2) Study of the shape of data
3) Measures of central and non central tendency
4) Measures of variability

Question 2

Frequency distributions are shown as

Answer 2

1) Tables 2) graphs (histograms or dotplots)

Question 3

Histograms

Answer 3

To display continuous data related to the frequency

Question 4

With small sample sizes we use

Answer 4

Dotplots

Question 5

Frequency distributions present different shape

Answer 5

1) skewed to the left
2) symmetric
3) skewed to the right

Question 6

If histograms show always decreasing or always increasing frequencies the distribution is said to be

Answer 6

J shaped

Question 7

If frequencies are decreasing in the left side of the histogram and increasing in the right side of the histogram the distribution is said to be

Answer 7

U shaped

Question 8

If frequencies are decreasing in the left side of the histogram and increasing in the right side of the histogram the distribution is said to be

Answer 8

U shaped

Question 9

Sometimes there are data that do not fall near any other values. These extremely high or low values are called

Answer 9

Outliers

Question 10

Sometimes there are data that do not fall near any other values. These extremely high or low values are called

Answer 10

Outliers

Question 11

How do we calculate percentages

Answer 11

Dividing counts by the sample size and multiplying by 100

Question 12

For which kind of variables do bar charts display frequency distribution?

Answer 12

For discrete variables

Question 13

For which kind of variables do histograms display frequency distributions ?

Answer 13

For continuous variables

Question 14

Most common measures of central tendency

Answer 14

Mean and median

Question 15

What is the median

Answer 15

Middle value in a sorted list of data

Question 16

When is median a better indicator of the central tendency of data ?

Answer 16

In skewed data or data with extreme values

Question 17

When do we have a negative skewness?

Answer 17

When the median is bigger than the mean

Question 18

When do we have symmetry?

Answer 18

When the mean is equal to the median

Question 19

When do we have positive skewness?

Answer 19

Then the median is smaller than the mean

Question 20

Measures of non central tendency for numerical data

Answer 20

Quantiles

Question 21

First quartile

Answer 21

25% of the data are less than Q1 and 75% are greater than Q1

Question 22

Second quartile

Answer 22

50% of the data are less than Q1 and 50% of the data are greater

Question 23

Third quartile

Answer 23

75% of the data are less than Q3 and 25% are greater than Q3

Question 24

Quantiles are

Answer 24

Values at specific positions in the sorted list of data

Question 25

What does the term variability refers to?

Answer 25

How spread out the data is

Question 26

Which are the four widely used measures of variation?

Answer 26

Range, interquartile range, variance and standard deviation

Question 27

What is the range?

Answer 27

The difference between the maximum value and the minimum value in a data set

Question 28

What is the interquartile range?

Answer 28

The difference between the first quartile and the third quartile

Question 29

Standard deviation quantifies variability in the same …

Answer 29

Units of measure

Question 30

Standard deviation quantifies variability in the same …

Answer 30

Units of measure

Question 31

The greater the standard deviation is

Answer 31

The greater the spread of the data

Question 32

The greater the standard deviation is

Answer 32

The greater the spread of the data

Question 33

How to calculate the standard deviation

Answer 33

The square root of variance

Question 34

How to calculate the coefficient of variation

Answer 34

Standard deviation/ mean x 100

Question 35

The higher the coefficient of variation

Answer 35

The higher the variability

Question 36

The coefficient of variation is useful to compare variability of

Answer 36

1) different variables 2) variables which are not measured in the same units of measurement 3) variables with different mean

Question 37

When is the coefficient of variation used

Answer 37

When we want to compare the variability among different sets of data or different variables

Question 38

Boxplots help to

Answer 38

Summarize the shape of data

Question 39

Histograms display

Answer 39

Frequency distributions for continuous variables

Question 40

Histograms display

Answer 40

Frequency distributions for continuous variables

Question 41

In a skew distribution

Answer 41

Use the mean as a measure of central tendency

Question 42

The standard deviation represents the average distance of data values from the mean True or false

Answer 42

True

Question 43

The standard deviation represents the average distance of data from the median True or false

Answer 43

False

Question 44

The greater the standard deviation the lower the variability

Answer 44

False

Question 45

The greater the standard deviation the lower the variability True or false

Answer 45

False

Question 46

The greater the standard deviation the greater the variability

Answer 46

True

Question 47

The coefficient of variation is typically useful to

Answer 47

Compare the variability among different sets of data or different variables