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Hypothesis: Link between independent and dependent variable, a prediction about what is going to happen. (observation)
Independent variable.: The variable that is changed. It's the one being investigated. Where possible, use units!
Dependent variable: The variable that is measured. Where possible, put units!
Control variables: The factors that are kept the same to make it a fair test.
- Preliminary work: Used to identify what factors can been controlled, how to set experiment up, how to minimise uncontrollable variables.
- Here the accuracy of a method is determined.
Validity: Answering the question posed.
Fair?: All variables are the same except the one we are testing
Reliable: A measure of the extent that the investigation gives the same result, i.e. the consistency of the data
- Repetition: Do it again!
- Replication: Others, using the same equipment, do the same investigation.
Accuracy: Closeness to the true value
- "Can go down to 25th decimal place" - Holland
Precision: The degree of detail the equipment allows.
Risk assessment: To reduce the chances of inquiry.
Ethical considerations:
- Anonymity
- Confidentiality
- Voluntary participation
- Can withdraw at any point
- Informed consent
Results: (graph)
- Title
- Independent variable on the x-axis
- Dependent variable on the y-axis
- Totals + averages
- Units
A stopwatch records to 2 decimal places (100s of seconds). When using stopwatch, record seconds, rather than 100s or 10s of seconds.
Measure equipment! (in the method)
Justifying your strategy
Don't contradict yourself, using more precise stopwatch is not necessarily an improvement.
- e.g. average in 3 decimal places, when initial data was measured in whole numbers.
$6CO_{2} + 6H_{2}O \to C_{6}H_{12}O_{6}$
-4 -4 , 2x +1 -2, C 0
CO_2 is reduced - gain
H_2O is oxidised
