# Representation and Analysis of Experimental Results

In this worksheet, combustion of wax is the basis for taking the student through representing and analysing experimental results.

Key stage:  KS 4

Curriculum topic:  Working Scientifically: Analysis and Evaluation

Curriculum subtopic:  Collecting, Presenting and Analysing Data

Difficulty level:

### QUESTION 1 of 10

Hydrocarbons are substances made from carbon and hydrogen only, for example see this diagram:

Depending on their content of carbon and hydrogen, hydrocarbons burn at different rates. Candles are made from wax, which is a hydrocarbon. Any burning needs oxygen to be present.

A group of pupils researched how long a candle burns for in different volumes of jars, when the jar covers the candle. Different volumes provide different amounts of air, i.e. oxygen, and so they burn for different times.

This is the table of their results:

Jar volume

Repeat 1

Time (s)

Repeat 2

Time (s)

Repeat 3

Time (s)

100 ml  6.5  7  13
200 ml  13  14  13.5
500 ml  30  34  32
1000 ml  61  63  63.5

This is the results table again.

Jar volume

Repeat 1

Time (s)

Repeat 2

Time (s)

Repeat 3

Time (s)

100 ml  6.5  7  13
200 ml  13  14  13.5
500 ml  30  34  32
1000 ml  61  63  63.5

What is the repeat in this experiment?

They repeated the experiment with three different volumes of jars.

They repeated the same procedure for each volume of jar three times.

They wrote their results in a table.

An average is the sum of the values of all the attempts divided by the number of attempts.

In our example, for the 100 ml jar, the students did the following calculations:

6.5 + 7 + 13 = 26.5

26.5 divided by 3 equals 8.8

The students filled out their Average time column like this:

Jar volume

Repeat 1

Time (s)

Repeat 2

Time (s)

Repeat 3

Time (s)

Average time

(s)

100 ml  6.5  7  13  8.8
200 ml  13  14  13.5  13.5
500 ml  30  34  32  31
1000 ml  61  63  63.5  62.5

Calculate the average in the other volumes and spot the mistake in their table.

For the 200 ml jar the average is 14.

For the 500 ml jar the average is 32.

For the 1000 ml jar the average is 63.

This is the table of results again with all the correct averages.

Jar volume

Repeat 1

Time (s)

Repeat 2

Time (s)

Repeat 3

Time (s)

Average time

(s)

100 ml  6.5  7  13  8.8
200 ml  13  14  13.5  13.5
500 ml  30  34  32  32
1000 ml  61  63  63.5  62.5

To gain maximum marks in your controlled assessment (coursework), you must identify anomalous results. Some exam boards call them outliers, especially when they are identified on a graph (we will look at that later). They are measurements that are very different than the others for the same volume.

Spot the anomalous results in the table above.

repeat 3 for 100 ml

repeat 2 for 200 ml

repeat 3 for 1000 ml

Anomalous results should not be included in the averages in order to gain maximum marks. You must state that you are doing this in your coursework.

Jar volume

Repeat 1

Time (s)

Repeat 2

Time (s)

Repeat 3

Time (s)

Average time

(s)

100 ml  6.5  7  13

200 ml  13  14  13.5  13.5
500 ml  30  34  32  32
1000 ml  61  63  63.5  62.5

Recalculate the average time for the 100 ml jar excluding the anomalous result identified in the previous question. This is now underlined.

13.5

4.5

6.75

The image shows a selection of charts and graphs.

When a variable has different numbers and can take any value (for example height), it is best to use a line graph. When the variable cannot take any value and/or shows a characteristic (for example eye colour), it is best to use a bar graph

What type of graph would you use for the candle experiment?

line graph

bar graph

pie chart

The image below shows a straight line graph. Sometimes not all the points on the graph would be on a straight line. A line of best fit should then be drawn. This is a line that goes through as many of the points as possible, and in our experiment it should start from the zero point.

Where do you think you would find anomalous results on a line graph?

They would be points exactly on the line.

They would be points not plotted at all.

They would be points that are far from the line.

This is the correct results table.

Jar volume

Repeat 1

Time (s)

Repeat 2

Time (s)

Repeat 3

Time (s)

Average time

(s)

100 ml  6.5  7  13  6.75
200 ml  13  14  13.5  13.5
500 ml  30  34  32  32
1000 ml  61  63  63.5  62.5

Analyse the results and determine whether this statement is true or false.

The time taken for the candle to extinguish in the 100 ml jar is roughly half the time taken for the 200 ml jar.

true

false

This is the correct results table again.

Jar volume

Repeat 1

Time (s)

Repeat 2

Time (s)

Repeat 3

Time (s)

Average time

(s)

100 ml  6.5  7  13  6.75
200 ml  13  14  13.5  13.5
500 ml  30  34  32  32
1000 ml  61  63  63.5  62.5

Analyse the results and identify the correct statement.

The time taken for the candle to extinguish in the 100 ml jar was roughly one third of the time in the 500 ml jar.

The time taken for the candle to extinguish in the 100 ml jar was roughly one tenth of the time in the 1000 ml jar.

The time taken for the candle to extinguish in the 100 ml jar was roughly one fifth of the time in the 1000 ml jar.

Jar volume

Repeat 1

Time (s)

Repeat 2

Time (s)

Repeat 3

Time (s)

Average time

(s)

100 ml  6.5  7  13  6.75
200 ml  13  14  13.5  13.5
500 ml  30  34  32  32
1000 ml  61  63  63.5  62.5

Have another look through the results and identify another correct statement.

The time taken for the candle to extinguish in the 1000 ml jar was roughly three times the time in the 500 ml jar.

The time taken for the candle to extinguish in the 1000 ml jar was roughly ten times the time in the 100 ml jar.

The time taken for the candle to extinguish in the 500 ml jar was roughly double the time in the 100 ml jar.

It is advisable in scientific research to find an experiment similar to yours, so you can compare the results. This is called secondary evidence.

In our experiment, we could search the internet for results of another group of people that did the same. Choose the most appropriate secondary evidence from the list.

a similar study from a privately owned website

a similar study from an old scientific journal

a similar study from a current research team in a university

• Question 1

This is the results table again.

Jar volume

Repeat 1

Time (s)

Repeat 2

Time (s)

Repeat 3

Time (s)

100 ml  6.5  7  13
200 ml  13  14  13.5
500 ml  30  34  32
1000 ml  61  63  63.5

What is the repeat in this experiment?

They repeated the same procedure for each volume of jar three times.
EDDIE SAYS
The students took the same measurement for each volume of jar three times. This is essential to ensure their results are reliable. For example, if one of the measurements was very different from the others, it would mean they made a mistake or there was an error due to equipment and so on.
• Question 2

An average is the sum of the values of all the attempts divided by the number of attempts.

In our example, for the 100 ml jar, the students did the following calculations:

6.5 + 7 + 13 = 26.5

26.5 divided by 3 equals 8.8

The students filled out their Average time column like this:

Jar volume

Repeat 1

Time (s)

Repeat 2

Time (s)

Repeat 3

Time (s)

Average time

(s)

100 ml  6.5  7  13  8.8
200 ml  13  14  13.5  13.5
500 ml  30  34  32  31
1000 ml  61  63  63.5  62.5

Calculate the average in the other volumes and spot the mistake in their table.

For the 500 ml jar the average is 32.
EDDIE SAYS
The students made a mistake for the 500 ml jar. The correct average time is 32.
• Question 3

This is the table of results again with all the correct averages.

Jar volume

Repeat 1

Time (s)

Repeat 2

Time (s)

Repeat 3

Time (s)

Average time

(s)

100 ml  6.5  7  13  8.8
200 ml  13  14  13.5  13.5
500 ml  30  34  32  32
1000 ml  61  63  63.5  62.5

To gain maximum marks in your controlled assessment (coursework), you must identify anomalous results. Some exam boards call them outliers, especially when they are identified on a graph (we will look at that later). They are measurements that are very different than the others for the same volume.

Spot the anomalous results in the table above.

repeat 3 for 100 ml
EDDIE SAYS
Repeat 3 for 100 ml is way out of the range of the first two measurements, i. e. 13 s is a much longer time than 6.5 s and 7 s.
• Question 4

Anomalous results should not be included in the averages in order to gain maximum marks. You must state that you are doing this in your coursework.

Jar volume

Repeat 1

Time (s)

Repeat 2

Time (s)

Repeat 3

Time (s)

Average time

(s)

100 ml  6.5  7  13

200 ml  13  14  13.5  13.5
500 ml  30  34  32  32
1000 ml  61  63  63.5  62.5

Recalculate the average time for the 100 ml jar excluding the anomalous result identified in the previous question. This is now underlined.

6.75
EDDIE SAYS
The correct calculation is 6.5 + 7 = 13.5
13.5 divided by 2 equals 6.75, so the last option is correct. For the second option someone would have to add the first two repeats and divide by 3, but that would be wrong, because the repeats averaged are two and not three, since the anomalous one was excluded. The first option is wrong, because it is just a sum of the repeats and not an average.
• Question 5

The image shows a selection of charts and graphs.

When a variable has different numbers and can take any value (for example height), it is best to use a line graph. When the variable cannot take any value and/or shows a characteristic (for example eye colour), it is best to use a bar graph

What type of graph would you use for the candle experiment?

line graph
EDDIE SAYS
The best choice would be a line graph; this would give you maximum marks. A bar graph could also be used, but would give you half the marks you could get.
• Question 6

The image below shows a straight line graph. Sometimes not all the points on the graph would be on a straight line. A line of best fit should then be drawn. This is a line that goes through as many of the points as possible, and in our experiment it should start from the zero point.

Where do you think you would find anomalous results on a line graph?

They would be points that are far from the line.
EDDIE SAYS
Anomalous results would be far from the line. This is because they do not fit in the general pattern of the results, as they were the products of mistakes and errors.
• Question 7

This is the correct results table.

Jar volume

Repeat 1

Time (s)

Repeat 2

Time (s)

Repeat 3

Time (s)

Average time

(s)

100 ml  6.5  7  13  6.75
200 ml  13  14  13.5  13.5
500 ml  30  34  32  32
1000 ml  61  63  63.5  62.5

Analyse the results and determine whether this statement is true or false.

The time taken for the candle to extinguish in the 100 ml jar is roughly half the time taken for the 200 ml jar.

true
EDDIE SAYS
The statement is true. The correct repeats (1 and 2) for the 100 ml jar are roughly half of the ones for 200 ml. The same is true for their averages. For example, average 6.75 is half of 13.5.
• Question 8

This is the correct results table again.

Jar volume

Repeat 1

Time (s)

Repeat 2

Time (s)

Repeat 3

Time (s)

Average time

(s)

100 ml  6.5  7  13  6.75
200 ml  13  14  13.5  13.5
500 ml  30  34  32  32
1000 ml  61  63  63.5  62.5

Analyse the results and identify the correct statement.

The time taken for the candle to extinguish in the 100 ml jar was roughly one tenth of the time in the 1000 ml jar.
EDDIE SAYS
The second statement is true. The correct repeats (1 and 2) for the 100 ml jar are roughly one tenth of the ones for 1000 ml. The same is true for their averages.
• Question 9

Jar volume

Repeat 1

Time (s)

Repeat 2

Time (s)

Repeat 3

Time (s)

Average time

(s)

100 ml  6.5  7  13  6.75
200 ml  13  14  13.5  13.5
500 ml  30  34  32  32
1000 ml  61  63  63.5  62.5

Have another look through the results and identify another correct statement.

The time taken for the candle to extinguish in the 1000 ml jar was roughly ten times the time in the 100 ml jar.
EDDIE SAYS
The second statement is true. The correct repeats (1 and 2) for the 100 ml jar are roughly one tenth of the ones for 1000 ml. The same is true for their averages.
• Question 10

It is advisable in scientific research to find an experiment similar to yours, so you can compare the results. This is called secondary evidence.

In our experiment, we could search the internet for results of another group of people that did the same. Choose the most appropriate secondary evidence from the list.

a similar study from a current research team in a university
EDDIE SAYS
Secondary evidence is most reliable when they are from university scientists and published recently, so the last statement is correct.
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