Theory: Statement designed to explain a large set of related observations that has
been confirmed by experimentation. Theories are NOT WRONG
Variable: anything that can change or does change during experiment.
Qualitative Data: observations made without any measurements (color)
Quantitative Data: observations made more
precise with measurements (numbers)
Double blinding: investigators do not know which treatment effect they are
observing, nor do the subjects know what treatment they are getting.
Control: variables whose values are prevented from changing. Its function is to verify
that the results are caused by the independent variable and no other factor.
Control experiment: an experiment in which all the variables are the same
except for one (the value of the independent variable
Common Questions
How to improve the reliability: what METHOD was wrong?
Never say the equipment, and if there was a problem with
the equipment, find a practical solution
Improving reliability
Repeat the experiment two or three times more and get an average which is more
reliable
- Conduct the experiment over a wider range of independent values and get a wider
range of answers
- DO. NOT. BLAME. YOUR. EQUIPMENT.
If you are asked to state your results, always state the trend in data then back this
up by quoting data from the table or graph.
Give full, detailed description of your observation
List the controlled variables – THEN say how each was controlled
Avoiding errors:
prevent cross contamination by washing apparatus between uses
- Bending down to eye level so that apparatus is precise
- Keeping measurements constant by ensuring that the water level in the syringe was
the same each time by measuring at eye level or ensuring the temperature was
always constant by using a thermometer.
Designing your own experiment
Only change one variable at a time (independent variable).
Mention the quantity of substance and the control.
Always mention that you are going to measure and how you are going to measure.
Make sure you mention ever single apparatus (tick off if need
be). Be. Very. Specific.