51ºÚÁÏ

This lesson guides students through the use of the chi-squared test to determine the significance of the difference between observed and expected results. It is fully-resourced with a detailed PowerPoint and accompanying student workbooklet that have been designed to cover this aspect of the A-level Biology specification.

The lesson includes a step-by-step guide that demonstrates how students should select an appropriate statistical test ( from Chi squared, Spearman’s rank, Student’s t-test and paired t-test). It also explain how the chi-squared (χ2) test can be used to determine the significance of the difference between observed and expected results with a worked example.

The student workbook has a series of chi squared calculation questions of increasing difficulty using a range of biology topics with including ecology, antibiotic resistance in bacteria, phenotypic ratios in a dihybrid cross and mitosis. The accompanying PowerPoint highlights the method to calculate the expected numbers and then how to find the critical value in order to compare it against the chi-squared value for each question.