9700_y16_sy

Cambridge International AS and A Level Biology 9700 syllabus General syllabus requirements and information
At A Level only
Candidates should be able to:
• have sufficient understanding of probability to understand genetic ratios
• understand the principles of sampling as applied to biological situations and data
• understand the importance of chance when interpreting data
• use the Petersen or Lincoln index to calculate an estimate of population size using mark-releaserecapture
data and the formula:
N = n × n 1 2
m 2
N = population estimate
n 1
= number of marked individuals released
n 2
= number of individuals (both marked and unmarked) captured
m 2
= number of marked individuals recaptured
• calculate Simpson’s Index of Diversity (D) using the formula:
n 2
D = 1–
NΣN NO
O
n = number of individuals of each type present in the sample (types may be species and/or higher taxa
such as genera, families, etc.)
N = the total number of all individuals of all types
• calculate standard deviation and standard error
• understand the benefits of using standard error and 95% confidence intervals (95%CI) to make
statements about data and to use as error bars on graphs
• understand the difference between correlation and causation; use Spearman’s rank correlation and
Pearson’s linear correlation to test for correlation
• use the χ 2 test and the t-test
• use a spreadsheet program for analysing and presenting data, making calculations and carrying out
statistical tests.
5.1.1 Notes on the use of statistics in biology
Candidates should know the distinction between descriptive statistics and statistical tests. They should
also appreciate the requirement to choose appropriate statistical methods before planning an investigation
in which they will either collect primary data or analyse secondary data. Candidates should have an
understanding of the different types of variable and also the different types of data they may collect or be
asked to analyse.
Descriptive statistics
For quantitative data, candidates should understand the difference between a normal distribution and a
distribution that is non-normal. Candidates should know appropriate descriptive statistical methods to
simplify their data. They should be able to use a calculator and/or spreadsheet program to find the mean,
median, mode, total range, interquartile range, standard deviation, standard error and the 95% Confidence
Interval (CI). Standard error (SE) and 95%CI are useful for expressing the reliability of an estimate of the
mean and for putting error bars on graphs. Candidates should understand how to apply these methods
and explain their significance for their own data and any given data. The 95%CI is determined as the
mean ±2 × SE.
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