key science skills

independent varibale

The variable controlled by the researcher that is deliberately changed

Only 1 independent variable should be included in the experiment. Otherwise, the researcher is unable to verify which independent variable caused the changes to occur in the dependent variable.

dependent variable

• the variable that changes in response to the independent variable

• these changes are observed, measured and recorded as data

• e.g test scores (dependent) changes due to the amount of studying (independent)

controlled variables

• all factors other than the dependent and independent variables.

• All other factors are kept constant throughout the experiment

• ensures that you can establish the relationship between the independent and dependent varibles

control group

• the control group is the group in an experiment that does not receive the variable you are testing

• no independent variables should be in the controlled experiment

• e.g Plants are not given in IV treatment (organic fertliser)

experimental group

• an experimental group is the group that receives the variable being testing in an experiment

• plants given the iV treatment (organic fertiliser)

qualitative data

• qualitative date is descriptive, not numerical and can be easily obersved and described but not measure

quantitive data

• quantitive data can be observed and measure and expressed numerically

systematic errors

• flaws in your scientific method or equipment which you can generally control

• affects the accuracy and validity of results

• examples - forgetting to zero a balance produces mass measurements that are always “off” by the same amount

• repeating an experiment will not reduce a systematic error. recognising the problem and fixing equipment will reduce the effect of the error

random errors

• random fluctuations in the readings of a measurement apparatus or individual errors

• eg. when reading the volume of liquid in a flask you may read the volume from a different angle each time

• repeating an experiment many times and finding an average will reduce the effect of a random error

limitations

limitations come serval sources and affect the quality of the data because

• experiments create artificial situations that do not necessarily represent real life situations

• while every effort is made to identify controlled variables and keep them constant through the course of the experiment, it is not always possible to identify and control of of these

accuracy

accurate data is close to the true known value for a measurement

precision

precise data is consisten the numbers/values are close to each other

validity

• valid results truly represents what you are trying to measure or describe in your investigation - your experiment actually measures what it is claiming to measure

reliability

reliable data is acheived when the results are found to be similar every time we perform the experiment

reproducibility

other scientists could follow your method and get the same results overs and over again