Data analysis

Question 1

What is quantitative data?

Answer 1

Results that can be counted, usually given as numbers.

Question 2

What is qualitative data?

Answer 2

Results that are expressed in words and non-numerical. They may take the form of a written description of the thoughts, feelings and opinions of participants, or a written account of what the researcher saw in an observation.

Question 3

What is nominal data?

Answer 3

Categories (e.g. cat, dog, fish)

Question 4

What is ordinal data?

Answer 4

A numerical scale that can be ordered but the units do not have standardised intervals (e.g. scale of 1-10, ranking 1st 2nd 3rd)

Question 5

What is interval data?

Answer 5

Data that is based on standardised numerical scales where the units are of equal, precisely defined size e.g. time, temperature, weight.

Question 6

Which measurement of central tendency for nominal?

Answer 6

Mode

Question 7

Which measurement of central tendency for ordinal?

Answer 7

Median

Question 8

Which measurement of central tendency for interval?

Answer 8

Mean

Question 9

Which measure of dispersion for nominal?

Answer 9

None

Question 10

Which measures of dispersion for ordinal?

Answer 10

Range

Question 11

Which measures of dispersion for interval?

Answer 11

Standard deviation

Question 12

What do measures of central tendencies do?

Answer 12

These tell us about the central (middle) values for a set of data. They are ‘averages’ i.e. ways of calculating typical values of a set of data.

Question 13

What do measures of dispersion do?

Answer 13

These tell us how dispersed or spread out the data items are

Question 14

What is a mean?

Answer 14

Calculated by adding up all of the numbers and dividing by the number of numbers you have. It can only be used with interval level quantitative data.

Question 15

What is a median?

Answer 15

The middle value in an ordered list. If there are two central values, the median is calculated by adding those two items and dividing by two. The median can be used with interval and ordinal quantitative data.

Question 16

What is a mode?

Answer 16

The most common data item. With nominal quantitative data, this is the category that has the highest frequency count. With interval and ordinal data, it is the data item that occurs most frequently. If two categories or data items have the same frequency, the data have two modes i.e. are bi-modal.

Question 17

What is a range?

Answer 17

This is the arithmetic distance between the top and bottom values in a data set.

Question 18

What is standard deviation?

Answer 18

This is a more precise way of measuring the spread of data. It is a measure of the average distance between each data item above and below the mean. Ideally, you want the standard deviation to be as low as possible (which shows you that the numbers are close to the mean i.e. low spread of data so that the results are consistent).

Question 19

When would a table be used?

Answer 19

For the measurements collected in a research study (referred to as ‘raw data’) – numbers before any descriptive statistics have been carried out. These can be set out in a table and/or summarised using measures of central tendency or measures of dispersion.

Question 20

When would a bar chart be used?

Answer 20

Bar charts are mainly used for nominal data (i.e. not continuous data). In a bar chart, there should be gaps between the bars to show the lack of continuity.

Question 21

When would scattergrams be used?

Answer 21

These are used for correlations (relationships). As it is a correlation, there is no independent or dependent variable, only co-variables. Therefore, it does not matter which variable goes on each axis.

Question 22

When would histograms be used?

Answer 22

When the data is continuous rather than discrete like in a bar chart. The x-axis is made up of equal-sized intervals of a single category while the y-axis represents the frequency within each interval.

Question 23

When would a line graph be used?

Answer 23

There has to be continuous data on the x axis for this to be used. The y axis should be frequency and a cross is placed to the middle of where the top of the bar would be.

Question 24

What does a normal distribution look like?

Answer 24

This is a classic bell-shaped curve.
· The mean, median and mode are all in the exact mid-point
· The distribution is symmetrical around the mid-point
· The dispersion of scores or measurements either side of the mid-point is consistent and can be expressed in standard deviations.

Question 25

What does a positively skewed distribution look like?

Answer 25

Most of the scores are bunched towards the left e.g. a test of normal behaviour to depression. There are a few high scores which affects the mean making it always higher than the median and mode in a positive skew. (mode -> median -> mean)

Question 26

What does a negatively skewed distribution look like?

Answer 26

This is when most of the scores are bunched towards the right e.g. an easy test. The mode is to the right of the mean because the mean is affected by the high scores on the left. (mean-> median -> mode)