Presenting Data Graphically

Question 1

at are the different ways to present data graphically?

Answer 1

Bar charts
Scatter diagrams
Histograms
Line graphs

Question 2

When are bar charts used?

Answer 2

To represent discrete data where the data is in categories, which are placed on the x axis

Question 3

What is on the x and y axis of bar charts?

Answer 3

X axis - the catagories
Y axis - mean or frequency

Question 4

When drawing a bar chart what do you need to keep in mind?

Answer 4

Columns don’t touch and they have equal width or spacing

Question 5

What is the difference between a bar chart and a histogram?

Answer 5

Bar charts present discrete data where else histograms present continuous data

Question 6

When are scatter diagrams used?

Answer 6

For measuring the relationship between 2 variables

Question 7

What do you need to keep in mind when drawing a scatter diagram?

Answer 7

Data from 1 variable is on 1 axis whilst data from the other variable is on the y axis
You plot an x on the graph where the 2 variables meet
The patterns of the plotted points may then reveal a correlation

Question 8

Which type of data do histograms present?
Why?

Answer 8

Continuous data because they present data on a continuous scale

Question 9

What do you need to keep in mind when drawing a histogram?

Answer 9

Columns touch because each one forms a single score (interval) on a related scale
These scales (intervals) are placed on the x axis
The height of the column shows the frequency

Question 10

When may a line graph be used?

Answer 10

To present continuous data

Question 11

What do line graphs show?

Answer 11

They show where the mid point of each column on a histogram would be

Question 12

What are line graphs useful for?

Answer 12

To present continuous data, between two possible variables

Question 13

Define correlation?

Answer 13

When 2 or more variables (co-variables) are measured in order to identify if there is a relationship between then

Question 14

How do you measure correlation

Answer 14

A single numerical value (PMCC or r)

Question 15

What are the 3 types of correlation?

Answer 15

Positive
Negative
No correlation

Question 16

What is happening to the variables in positive correlation?
Draw a graph showing positive correlation?

Answer 16

Question 17

What is happening to the variables in negative correlation?
Draw a graph showing negative correlation?

Answer 17

Question 18

What is happening to the variables when there is no correlation?
Draw a graph showing no correlation?

Answer 18

Question 19

What is the correlation co-efficient?

Answer 19

A number between -1 and 1
As r tends towards -1 it means that the data is getting stronger negative
As r tends towards 1 it means that the data is gettibng more strong positive
R=0 there is no correlation

Question 20

What is important to remember about correlation?

Answer 20

You can’t state a cause and effect by using correlation

Question 21

What are the advantages of using correlation?

Answer 21

They can be used when it would be unethical/ unpractical to conduct an experiment
If correlation is significant, then further investigations are justified
If correlation is significant, you can rule out a casual relationship

Question 22

What are the disadvantages of using correlation?

Answer 22

Correlation analysis can’t demonstrate a cause and effect relationship between variables
There may be other unknown variables that can explain why the co-variables being studied are linked
Extraneous variables may lead to false conclusions

Question 23

What is an example of a famous piece of research?

Answer 23

Milgriam’s variation using LOC and obedience scores

Question 24

Why do we add 1 after calculating the range?

Answer 24

To avoid rounding errors

Question 25

What is a line graph also know as?

Answer 25

A frequency polygon