Peach Pack 3

Question 1

What is the difference between DESCRIPTIVE statistics, and INFERENTIAL statistics?

Answer 1

Descriptive statistics describe the data – they make it easier to understand. They include measures of central tendency, and measures of dispersion.
Inferential statistics explain whether the results are significant or due to chance.

Question 2

What is the mean?

Answer 2

Sum of values/number of values

interval level

Question 3

What is the median?

Answer 3

The central value (ordinal level)

Question 4

What is the mode?

Answer 4

Most frequently occurring value

nominal level data

Question 5

What are the strengths of the mean?

Answer 5

• Uses all the information in a set of data as operating at the interval level
• Most powerful and sensitive
• Representative of the data

Question 6

What are the weaknesses of the mean?

Answer 6

• Can be distorted by skewed data
• Not useful for ranked (ordinal) data or nominal level data
• Sometimes does not reflect reality

Question 7

What is the strength of the median?

Answer 7

Not distorted by skewed data

Question 8

What is a strength of the mode?

Answer 8

Not influenced by skewed data

Question 9

What are the disadvantages of the median?

Answer 9

• Less sensitive to the data
• Less meaningful with small sets of data
• Not useful with nominal level data

Question 10

What are the weaknesses of the mode?

Answer 10

• not sensitive

- Not useful with many modes

Question 11

What is standard deviation?

Answer 11

How much on average each of the scores in a data set deviates from the mean.

Question 12

How can you estimate the outcome of a calculation?

Answer 12

Round all of the numbers to 1 significant figure.

Then do the calculation with these numbers

Question 13

What is the rule for multiplying powers in standard form?

Answer 13

•To multiply powers you add

Question 14

What is the rule for dividing powers in standard form?

Answer 14

To divide powers you subtract

Question 15

What are descriptive statistics and why are they used?

Answer 15

Descriptive statistics are used to describe the main trends in the data.
They are used to summarise the raw data from research into a more meaningful form to help researchers draw conclusions from the results.

Question 16

What is a measure of central tendency?

Answer 16

A measure of central tendency is ‘the value in a group of values which is the most typical’ for the data set.

Question 17

Identify the 3 measures of central tendency

Answer 17

• Mean
• Mode
• Median

Question 18

What is a measure of dispersion?

Answer 18

They are a measure of weather the scores are clustered closely around the mean or are scatted widely.

Question 19

What is the range?

Answer 19

The range is the difference between the largest and smallest scores in the data set.

Question 20

What are the advantages of the range?

Answer 20

Quick and easy to calculate

Question 21

What are the limitations of the range?

Answer 21

• Less effective with skewed data

- Very rough estimate of dispersion

Question 22

What are the advantages of standard deviation?

Answer 22

• Sensitive to the data as every score is used
• Most powerful
• Likely to be representative of the data
• Less effected by skewed data than the range

Question 23

What are the disadvantages of standard deviation?

Answer 23

-Can take a long time to calculate by hand

Question 24

Explain how the median is calculated

Answer 24

1. Put the values in order from smallest to largest
2. Select the middle value
3. If there are two middle values, use the mean of the two

Question 25

When are bar charts used?

Answer 25

Question 26

What are pie charts used to show?

Answer 26

A pie chart is a way of summarizing a set into data in categories.
Or displaying proportions.

Question 27

What do scatter diagrams show?

Answer 27

Scatter diagrams are used to show a relationship between two co variables.
The data points are plotted but never joined up.

Question 28

What is the equation to workout the degree of each proportion in a pie chart?

Answer 28

(No. Out of total/ total) x 360 = degrees of a circle

Question 29

Describe histograms

Answer 29

The histogram is used to summarise data that are measured on an interval scale.
In a histogram, frequency is shown by the area of the column.
The area of the rectangle represents the proportions of frequency of observations falling into that group.

Question 30

How do you calculate frequency density for histograms?

Answer 30

Frequency density = frequency ÷ class width

Question 31

In histograms the data is continuous so there is no gaps in between the bars.
True or False

Answer 31

True

Question 32

What should the y axis be labelled in a histogram?

Answer 32

Frequency density

Question 33

Describe normal distribution

Answer 33

Question 34

Explain positively skewed distributions

Answer 34

When the mode < the median < mean the data is positively skewed.
This means the scores or measures are mainly towards the lower end of the distribution but there is a score that is very high.
The mean is pulled upwards (in a positive direction) towards this high
score.
The median stays in the middle of the distribution because it is not
influenced by the extreme score.
The mode, as the most frequently occurring score, will be at the peak
of the curve.

Question 35

Explain negatively skewed distributions

Answer 35

When the mean < the median < mode the data is negatively skewed.
This means the scores or measures are mainly towards the higher end of the distribution but there is a score that is
very low.
The mean is pulled downwards (in a negative direction) towards this low score.
The median stays in the middle of the distribution because it is not influenced by the extreme score.
The mode, as the most frequently occurring score, will be at the peak of the curve.

Question 36

What are the key things to remember when constructing a bar chart?

Answer 36

Question 37

What are the key things to remember when constructing a scatter diagram?

Answer 37

Question 38

When should you use a scatter diagram?

Answer 38