Descriptive Statistics Flashcards
1
Q
Nominal data
A
- No quantitative value
- Categorised
- No inherent order
- Mode
(e. g. Male or female, eye colour)
2
Q
Ordinal
A
- Ranked scale
- Non-numeric concepts
- Difference between values not know
- Can’t define mean
- Central tendency = median or mode
(e. g. level of satisfaction - ‘very happy’, ‘happy’ etc.)
3
Q
Interval
A
- Known differences between values
- No true zero
(e. g. temperature)
4
Q
Ratio
A
- Order
- Known differences between values
- True zero
(e. g. height/weight)
5
Q
Converting between types of data
A
- Divide numerical data into categories (e.g. small, medium, large)
- Or use interval/ratio data to rank individuals
6
Q
What are the three types of descriptive statistics?
A
- Central tendencies
- Dispersion
- Skewness and kurtosis
7
Q
Why are descriptive statistics important?
A
- First step in analysis
- Provide an overview of characteristics of data
- Summarise and describe a sample or population
8
Q
Central tendencies
A
- Grouping around the middle value
- Mean, median, mode
9
Q
Dispersion
A
- Measure of variation
- Range, interquartile range, standard deviation
10
Q
Skewness and kurtosis
A
Describe the shape of distribution
11
Q
Describe mean
A
- Sum of values divided by number of observations
- Interval or ratio
- Good for large data set with expected normal distribution
12
Q
What are the advantages/disadvantages of using mean?
A
+ All values are considered
- Distorted by extremes
13
Q
Describe median
A
- Values are ranked by magnitude
- Median is the middle value (or half way between two middle values)
- Ordinal, interval, ratio
- Most useful when using symmetrical data
14
Q
What are the advantages/disadvantages of using median?
A
+ Not influenced by extremes
- Widely differing data may have the same median
15
Q
Describe mode
A
- The most frequent value
- Nominal, ordinal
