Graph and Table drawing
Pulse rate (beats/m)
Starter - What’s wrong?
Running started
walking
Exercise started
Oxygen released
Time (min)
0 1 2 3
5
6 7 9
Time (min)
pulse rate
time
60
1
72
2
90.1
3
Which Graph?
When should you use each graph?
•
Line –
• A. IV is discontinuous and DV
continuously variable
•
Bar -
• B. between two continuous
variables, a causal link cannot
be assumed (usually as it is
one variable out of many)
•
Scattergram -
•
C. Between two continuous
variables, a likely causal link
between the IV and DV.
Presenting your graph
• Join with a curve if the trend is very clear and
you can predict the values in between the
points
• Join with straight lines when the trend is not
clear and the values in between the points
cannot be assumed/predicted
• Bar charts – bars must be separated from each
other. If the bars touch it is a histogram!
Complete the table below
Investigation
Effect of Temp on release
of oxygen from hydrogen
peroxide by catalase
Frequency of blood group
A in age groups 15-20 and
35-40
Effect of soil pH on
percentage of variegated
clover leaves
Effect of water potential
of surrounding solution on
water gain/loss of potato
tissue
Effect of intensity of
exercise on heart rate
Independent
Dependent
variable and type Variable and type
Type of graph
Complete the table below
Investigation
Independent
variable and
type
Dependent
Variable and type
Type of graph
Effect of Temp on release
of oxygen from hydrogen
peroxide by catalase
Temperature
(continuous)
Volume of oxygen
(continuous)
Line
Frequency of blood group Ages
Frequency
A in age groups 15-20
(discontinuous) (continuous)
and 35-40
Bar
Effect of soil pH on
percentage of variegated
clover leaves
pH
(continuous)
Scattergram
Effect of water potential
of surrounding solution
on water gain/loss of
potato tissue
Water potential Change in mass
(continuous)
(continuous)
Line (may need +
and – values)
Effect of intensity of
exercise on heart rate
Intensity of
exercise
(continuous)
line
percentage of
clover
(continuous)
Heart rate
(continuous)
(can’t control other
variables in the field)
Other key words
• Mean
A. The difference between the lowest and
highest values. To calculate: e.g. In {4, 6, 9, 3,
7} the lowest value is 3, and the highest is 9, so
it is 9 − 3 = 6.
• Median
B. The average of the numbers: a calculated
"central" value of a set of numbers.
To calculate: Just add up all the numbers, then
divide by how many numbers there are
• Mode
• Range
C. The middle number (in a sorted list of
numbers).
To calculate: place the numbers you are given
in value order and find the middle number.
D. The number which appears most often in a
set of numbers.
Table rules
Tables
The following guidelines should be followed when presenting
results in tables.
• All raw data in a single table with ruled lines and border.
• Independent variable (IV) in the first column; dependent
variable (DV) in columns to the right
(for quantitative observations) OR descriptive comments in columns
to the right (for qualitative observations).
• Processed data (e.g. means, rates, standard deviations) in
columns to the far right.
• No calculations in the table, only calculated values.
Tables
• Each column headed with informative description (for qualitative
data) or physical quantity and correct SI units (for quantitative
data); units separated from physical quantity using either brackets
or a solidus (slash).
• No units in the body of the table, only in the column headings.
• Raw data recorded to a number of decimal places and significant
figures appropriate to the least accurate piece of equipment used
to measure it.
• All raw data recorded to the same number of decimal places and
significant figures.
• Processed data recorded to up to one decimal place more than
the raw data.
Graph rules
The following general guidelines should be followed
when presenting data in graphs:
• The type of graph used (e.g. bar chart,
histogram, line graph, pie chart or scattergram)
should be appropriate to the data collected.
• The graph should be of an appropriate size to
make good use of the paper.
• There should be an informative title, and axes
should be fully labelled with units.
Bar charts and histograms
• These are used when the dependent variable on the y-axis is discrete,
i.e. whole numbers,
• fractions are impossible and the data under consideration deal with
frequencies.
• Bar charts are used when the independent variable is non-numerical,
e.g. the number of different insect species found on trees. These data
are discontinuous.
• They can be made up of lines, or blocks of equal width, which do not
touch.
• The lines or blocks can be arranged in any order, but it can aid
comparison if they are arranged in descending order of size.
• Histograms can be used if the data is discrete but continuous
Data Handling - Worksheet
The data from table 3.1 can be organised into
classes. Fill in the table below.
Plot the most suitable graph of the data above.
Draw your graph
• Use your data to draw a graph.
• Are the data continuous or non- continuous?
• What sort of graph should you draw?
Peer Assess table and graph
• STAR time – make improvements in purple.
Answers
• Graph should be a histogram (bars touch as x axis is
continuous)
• Should be a key as two sets of data
• X axis height (mm)
• Y axis number of dog whelks per class (or /class)
• Good use of paper and equidistant axes