Research Methods- Descriptive Statistics

Question 1

Measures of Central Tendency:

Answer 1

A single value that summarises a set of data by identifying the typical value of the data set, also known as an average.

Question 2

Mode:

Answer 2

The most frequent score in a quantitative data set. If there are two modes, the data is bi-modal, and if there are more than two modes, the data set is multimodal.

Question 3

Mode
Advantages

Answer 3

The mode is not distorted by extreme scores called outliers

The mode is helpful for discrete numbers; for example, it can make more sense to say the average family has two children than 1.89 children.

Giving the modal group is the only way of giving the average of data in
categories(e.g. average pet choice)

Question 4

Mode
Disadvantages

Answer 4

X There can be no modes if every value is different or multiple modes; this is especially likely in small data sets. This means in some cases, the mode does not give an exact average value.

X The mode does not include all of the values in its calculation, so it is not as
sensitive as the mean measure of central tendency.

Question 5

Median:

Answer 5

The value in the central position of a data set.

Question 6

How is median calculated ?

Answer 6

The median is calculated by ordering the values from lowest to highest and selecting the value in the middle.
If there are an even number of data points, then the median is the halfway point between the two centre values.

Question 7

Median
Advantages

Answer 7

• As the median is the central value, its calculation is not affected by extreme outlier scores.

• The median is very easy to calculate.

Question 8

Median
Disadvantages

Answer 8

X The median score does not include all of the values in its calculation, so it is not as sensitive as the mean measure of central tendency.

X If there are an even number of data points, unlike the mode, the “typical” value will be a number that is not one of the recorded values.

Question 9

Mean:

Answer 9

The arithmetic/ mathematical average, calculated by adding all the values and then dividing by the number of values.

Question 10

Mean
Advantages

Answer 10

+All raw data points are used (represented) in calculating the mean. This means the mean is the most sensitive measure of central tendency

Question 11

Mean
Disadvantages

Answer 11

X Due to the sensitivity of the mean, the mean is distorted by extremely high or low values (outliers)

Question 12

The range:

Answer 12

The range is the difference between a data set’s highest and lowest values.

Question 13

How to calculate the range

Answer 13

To calculate the range subtract the smallest value in the data set from the largest (Adding one to this figure is also a correct way of stating the range.)

Question 14

The Range
Advantages

Answer 14

The range is easy to calculate, especially compared to the alternative measure of dispersion, the standard deviation.

Question 15

The Range
Disadvantages

Answer 15

X Extreme scores easily distort the value

X The range does not show if the scores are clustered around the mean
or more evenly spread out.

Question 16

The standard deviation:

Answer 16

The standard deviation (SD) is a complex calculation using all data points that produces a single value. The smaller the standard deviation more clustered (less spread out/variable) the values are around the mean.

Question 17

Standard deviation
Advantages

Answer 17

+ The SD includes all values in its calculation, making it more sensitive
than the range.

+ The SD provides information about the spread of scores.

Question 18

Standard deviation
Disadvantages

Answer 18

X Extreme scores also distort the SD

X The SD is significantly more difficult to calculate than the range.