Statistics and Graphs

Question 1

Mode +?

Answer 1

The mode is the simplest measure of central tendency to work out.
It is a good measure to use when the set of data contains exceptionally high or low scores as it is unaffected by extreme scores.

Question 2

Mode -?

Answer 2

However, it is the least sensitive measure of central tendency. it also tells us nothing about the other scores.

Question 3

Median +?

Answer 3

The median is easier than the mean to calculate.
The median is a good measure to use when the set of data contains exceptionally high or low scores as it is unaffected by extreme scores.

Question 4

Median -?

Answer 4

As it ignores most of the scores the median is not always representative.

It does not work well with small sets of data.

Question 5

Mean +?

Answer 5

As the mean makes use of all the data, it is a very powerful measure of central tendency.
It is a good measure to use when a set of data contains no exceptionally high or low values.

Question 6

Mean -?

Answer 6

But if there is an exceptionally high or low score, then the mean is not a good measure of central tendency to use as it can then be misleading.

Question 7

Range +?

Answer 7

The range is a simple calculation compared to the standard deviation.

Question 8

Range -?

Answer 8

It only takes into account the two most extreme values and this may be unrepresentative of the data set as a whole.

The range does not indicate whether values are closely grouped around the mean or spread out – we need the standard deviation to know this

Question 9

What does SD tell us?

standard deviation

Answer 9

The standard deviation tells us the average amount all scores deviate from the mean.

The larger the standard deviation, the greater the dispersion, or spread, of scores around the mean. This may suggest there were a few anomalous results.

A smaller standard deviation reflects the fact the data is tightly clustered around the mean, which might imply that all participants responded in a fairly similar way.

Question 10

SD overall?

Answer 10

While this is a little more time-consuming to calculate, this is the most sensitive measure of dispersion, using all the data available, and there are no important disadvantages.

Question 11

What do line graphs show?

Answer 11

Line graphs show information that is connected in some way, such as change over time.

Question 12

What do bar charts show?

Answer 12

Bar charts display data by using bars of different heights. It is the height of the bar that provides us with information.

Question 13

What are histograms?

Answer 13

Histograms are a special form of bar chart.

They differ from ‘standard’ bar charts in three different ways:

There are no gaps between the bars because the data is continuous rather than discrete

It is the area of the bar rather than the height of the bar that gives us detail about the size of the category

In a histogram, both the x-axis and the y-axis have a scale (compared to a bar chart where only the y-axis has a scale)

Question 14

What are scatter graphs?

Answer 14

Scattergrams are used to show associations between two sets of data (two co-variables).

Question 15

Normal distribution features?

Answer 15

Features:
Frequency distribution that has a classic bell shaped curve
The mean, median, mode are all in the exact midpoint
Most scores will be closely distributed near the midpoint
The distribution of frequency is symmetrical around the midpoint
Y-axis = frequency
X-axis = item of interest

Question 16

When do skewed distributions occur?

Answer 16

These occur when scores are not equally distributed around the mean.

Used when there are a number of extreme values to one side of the mid-score (lots of high scores or lots of low scores).

Question 17

What is a positive skew?

Answer 17

Majority (mode) of scores have low values
However, there is a ‘tail end’ of high scores
These extreme high scores then skew the mean to the right hand side of the mode – (i.e. in a positive skew the mean is GREATER than the mode)

Question 18

Whats a negative skew?

Answer 18

Majority (mode) of scores have high values
However, there is a ‘tail end’ of low scores
These extreme low scores then skew the mean to the left hand side of the mode – (i.e. in a negative skew the mean is SMALLER than the mode)