Descriptive Statistics

Question 1

What are the 4 levels of measurement?

Answer 1

• Nominal
• Ordinal
• Interval
• Ratio

Question 2

What is nominal data?
(one bullet point, explanation)

Answer 2

• Categorises and labels variables

Data can be classified into strict categories. Nothing can be in multiple categories

Question 3

What is ordinal data
(two bullet points, explanation)

Answer 3

• Categories and labels variables
• Ranks categories in order

Data has a rank. Doesn’t have equal intervals between each each unit. Based on subjective opinion

Question 4

What is interval data?
(three points, explanation)

Answer 4

• Categorises and labels variables
• Ranks categories in order
• Has equal gaps between data

Data measures something on a scale that includes units of equal size

Question 5

What is ratio data?
(four points, explanation)

Answer 5

• Categorises and labels data
• Ranks categories in order
• Has known, equal variables
• Has a true zero

Data has all the properties of interval data but has a true zero

Question 6

What are descriptive statistics used to do?

Answer 6

To describe or summarise the characteristics of a sample or data set

Question 7

What are the measures of central tendency?

Answer 7

• Mean
• Median
• Mode

Question 8

What are the measures of dispersion?

Answer 8

• Range
• Standard deviation

Question 9

What are the advantages and disadvantages of the mean?

Answer 9

+ Most sensitive measure as it uses every value in the data set to calculate an average

• Can be easily distorted by extreme values
• Can’t be used with nominal data

Question 10

What are the advantages and disadvantages of using the median?

Answer 10

+ Not affected by extreme values
+ Appropriate for ordinal data and can be easier to calculate

• Not as sensitive as the mean as the exact values arent used

Question 11

What are the advantages and disadvantages of using the mode?

Answer 11

+ Unaffected by extreme values and is useful for discrete data
+ Only method that can be used for nominal data

• Not useful when there are several modes like in interval or ratio data

Question 12

What are the advantages and disadvantages of using the range?

Answer 12

+ Identifies how spread out the data is

• Is affected by extreme values
• Doesn’t indicates whether the data is closely grouped to the mean or spread evenly

Question 13

What is the method of finding the standard deviation

Answer 13

• Work out the mean for the data set
• Subtract the mean from each data point
• Square the result
• Add these up
• Divide by n-1
• Finally, calculate the square root

Question 15

What are the advantages and disadvantages of using the standard deviation?

Answer 15

+ Precise measure because all the data values are used so can see the spread of data
+ Not as affected by extreme values because it doesn’t just look at the highest and lowest value in a data set

• It can hide characteristics of the data like extreme values because it indicates how far each value is rather than looking at each end of the data set

Question 16

What does a greater SD mean?

Answer 16

A greater spread of data

Question 17

What does a smaller SD mean?

Answer 17

Data values are clustered around the mean/ shorter spread of data