An agricultural scientist wants to investigate whether there is a linear correlation between the concentration of a particular soil nutrient, NNN (measured in parts per million, ppm), and the dry crop yield, YYY (measured in grams per square metre, g m−2\text{g m}^{-2}g m−2). The scientist collects data from 22 experimental plots.
The scientist decides to use a hypothesis test for the product-moment correlation coefficient (rrr) because they are looking for a linear association between two variables.
Explain one other condition about the data or the variables that must be satisfied for this test to be valid, referring specifically to the variables in this study.
121 exam-style questions on AQA A Level Psychology Inferential testing (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.