Processing Data in Biology (DP IB Biology): Revision Note

Processing data in Biology

• This is the "calculation" phase of your investigation

• Data processing involves applying mathematical calculations to your raw data to determine the final values you need to answer your research question

  • For example, calculating a percentage change in mass, a rate of reaction, or a standard deviation

• The goal is to carry out relevant and accurate calculations, including measures of data spread, and to present the results clearly

Principles of data processing

Carry out relevant and accurate data processing

• Your processed data should be presented in a new, clearly labelled table

  • It is good practice to show the raw data and processed data in separate tables

• Show your working clearly

  • For every type of calculation you perform, you must show one full, worked example

• Calculating a mean

  • When you have repeat trials (replicates), you must calculate a mean (average) value to use in your analysis

  • You should exclude any justified anomalous results from your calculation

• Calculating percentage change

  • In biology, we often measure the change in a variable relative to its initial value. This is useful for comparing samples that may not have had identical starting values

    • Percentage Change = ((Final Value – Initial Value) / Initial Value) × 100

• Calculating a rate

  • For enzyme experiments, you usually measure the time taken for an event

  • You must convert this into a rate to analyse the enzyme's activity

    • Rate = 1 / time (units will be s⁻¹) or Rate = change in a variable / time (e.g., cm³ s⁻¹)

• Calculating measures of dispersion

  • Due to the high variability in biological data, it is important to quantify the spread of your data around the mean

  • Standard deviation (SD) is the most common measure

    • A small SD indicates that the data points are clustered closely around the mean (high precision), while a large SD indicates a wider spread

• Significant figures

  • Your final calculated answer should be given to a number of significant figures that reflects the precision of the raw data used

    • The general rule is that your final answer should have the same number of significant figures as the least precise piece of data used in the calculation