Practical & Maths Skills: Getting Good Results

Question 1

Good results should be…

Answer 1

• Reliable
• Repeatable and reproducible
• Valid
• Accurate

Question 2

What are reliable results?

Answer 2

• Reliable results don’t vary much from the mean
• Reliability is reduced by random error
• Reliable results are sometimes referred to as precise results

Question 3

What are repeatable results?

Answer 3

• Repeatable means that if the same person repeats the experiment using the same methods and equipment, they will get the same results

Question 4

What are reproducible results?

Answer 4

• Reproducible means that if someone different does the experiment, using a slightly different method or piece of equipment, the results will still be the same

Question 5

What are valid results?

Answer 5

• Valid results answer the the original question

- To get valid results you need to control all the variables to make sure you’re only testing the thing you want to

Question 6

What are accurate results?

Answer 6

• Accurate results are really close to the true answer

- Human interpretation of a measurement (e.g determing a colour change) can reduce the accuracy of results

Question 7

How can we make sure our results are valid?

Answer 7

• Control other variables
- Variables are quantities that have the potential to change (e.g temperature, pH)

• Controls

• Negative controls
• Positive controls
• Control groups

Question 8

What are negative controls?

Answer 8

• Negative controls check that only the independent variable is affecting the dependent variable
- Negative controls aren’t expected to have an effect on the experiment

• When investigating the effect of light intensity on photosynthesis, a negative control could be where the experiement is carried out in the dark
• No photosynthesis should happen with this control

Question 9

What are positive controls?

Answer 9

• Positive controls should show what a positive result of the experiment should look like, to check that it is possible

• When testing for presence of glucose, carry out a Benedict’s test on a solution you know contains glucose
• This is to see what a positive test result looks like

Question 10

What are control groups?

Answer 10

• In studies, control groups are used
• Subjects in study are split into two groups - experimental group and control group
• The control group is treated in exactly the same way as the experimental group, except for the factor you’re investigating
• In a study with human participants, try keep variables like age and sex the same

Question 11

How can we ensure our results are reliable?

Answer 11

• Taking several repeat measurements and calculating the mean can reduce the effect of random error - increases reliability
• This may be done by increasing the sample size of an investigation
• This reduces the likelihood that the results are due to chance

Question 12

How can we ensure our results are repeatable and reproducible?

Answer 12

• Doing repeats and getting similar results show that your results are repeatable
• Also makes it more likely that the same results could be reproduced by another scientist in an independent experiment