● Qualitative data include all non-numerical information obtained from observations not from
● Quantitative data are obtained from measurements, and are always associated with random errors/
uncertainties, determined by the apparatus, and by human limitations such as reaction times.
● Propagation of random errors in data processing shows the impact of the uncertainties on the fi nal
● Experimental design and procedure usually lead to systematic errors in measurement, which cause
a deviation in a particular direction.
● Repeat trials and measurements will reduce random errors but not systematic errors.
SI units should be used throughout the programme.
Applications and skills
● Distinction between random errors and systematic errors.
● Record uncertainties in all measurements as a range (±) to an appropriate precision.
● Discussion of ways to reduce uncertainties in an experiment.
● Propagation of uncertainties in processed data, including the use of percentage uncertainties.
● Discussion of systematic errors in all experimental work, their impact on the results, and how they
can be reduced.
● Estimation of whether a particular source of error is likely to have a major or minor effect on the
fi nal result.
● Calculation of percentage error when the experimental result can be compared with a theoretical
or accepted result.
● Distinction between accuracy and precision in evaluating results.
● Note that the data value must be recorded to the same precision as the random error.
● The number of signifi cant fi gures in a result is based on the fi gures given in the data. When adding or
subtracting, the answer should be given to the least number of decimal places. When multiplying or
dividing the fi nal answer is given to the least number of signifi cant fi gures.
Student practical: Determining the change in volume of water and change in mass of boiled food