SIS Flashcards
Hypothesis
Expresses predicted relationship between independent and dependent variables
“If + change in independent + then + change in dependent”
Independent variable
The variable that is changed during an experiment to measure the effect on the dependent variable
Controlled varibale
Factors that are kept the same.
E.g. if you are increasing the concentration of acid that reacts with marble chips to see the effect on hydrogen gas production, they would be
- Amount of reactants (mass / volume)
- State of subdivision of solid reactant
- Temperature of reaction mixture
Dependent variable
Variable that is controlled in a chemical reaction in order to see the effect of changing the independent variable
Primary data
Data collected BY the person or group directly who are using it
Primary source
Report of data that was written BY those that collected the findings/data
Secondary data
Data that was collected by someone else to who is using it
Secondary source
A report of data complied from primary sources that were collected by someone OTHER than who is writing it
Validity
The extent to which an experiment actually measures what was intended
To be valid, an experiment should only change one variable (independent variable) and control others, because they could be the ones affecting the result and hence a valid inference could not be drawn.
Qualitative data
Data that is observable and catgorisable but not numerically measurable
Quantitative data
May be discrete (a solid #, like number of protons)
Or continuous (a scale that allows decimals)
Is measurable
Reliability
The degree to which an experiment consistently and repeatedly achieves the same result
To be considered more reliable, you should have
- Repeat trials (then average them)
- Have a greater sample size
- Repeat the entire experiment
Accuracy
The ability to obtain the correct measurement (which might be impaired by ERRORS, not due to not CONTROLLING something which would be validity)
You have to minimise systematic errors
I.e. you can’t just say ‘use more accurate equipment’ because that would reduce random measurement error
Focus on fundamental flaws with the experiment
Precision
Ability to consistently obtain the same measurement
Minimise random errors (e.g. using better equipment) to improve precision
Uncertainty
How far an experimental quantity possibly is from the true value due to ambiguity from measurement tool
