9700_y16_sy

Cambridge International AS and A Level Biology 9700 syllabus Practical assessment
Type of variable
Qualitative
categoric
ordered
Quantitative
Type of data
nominal, i.e. values or observations belonging to it can be sorted according to
category, e.g. colour of flowers, gender
ordinal, where values that can be placed in an order or rank and the interval
between them may not be equal, e.g. the order in which test-tubes containing
starch and iodine become colourless after adding amylase
continuous, which can have any value within a specific range and can be
expressed as a whole number, fraction or a decimal. It can be counted,
ordered and measured, e.g. body mass, leaf length
Evaluation
Using given data, candidates should be able to:
• Identify anomalous values in a table or graph of data and suggest how to deal with anomalies. Strategies
for dealing with such anomalies include:
– repeating the experiment until consistent results are obtained
– leaving out the affected data
• Suggest possible explanations for anomalous readings. Where investigations use familiar contexts that
have been explored during the course, candidates should be able to suggest possible causes for such
anomalies
• Assess whether the provided data has been replicated sufficiently and describe whether the range of
measured data was appropriate and the intervals between data was appropriate
• Explain why replicating data is important and the practical limits on replication
• Identify instances where:
– More measurements need to be taken with an increased or decreased value of the independent
variable in order to give a complete range of data values
– There are gaps in the range of the independent variable which reduce the information the
investigation can give
• Assess whether the method of measuring is appropriate for the dependent variable, for example, using
a pH meter is more likely to give more accurate and reliable results than using an indicator and a colour
chart to measure changes in pH
• Assess the extent to which selected variables have been effectively controlled, using given information,
for example, whether the temperature recorded was the same for each of a number of samples
• Use these evaluations and any given information to make informed judgements about:
– how much confidence can be put in any conclusions
– the validity of the investigation
– how much the data can be trusted for testing the hypothesis.
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