A quality control manager tests the null hypothesis H0:μ=25.0 gH_0: \mu = 25.0\text{ g}H0:μ=25.0 g against the alternative hypothesis H1:μ<25.0 gH_1: \mu < 25.0\text{ g}H1:μ<25.0 g for the mean active ingredient in a batch of tablets. The test results lead the manager to retain H0 H_0\,H0 and approve the batch for shipment. In reality, the batch is deficient, with a true mean of only 23.8 g. Which of the following correctly identifies and explains the error committed?
A Type I error, because the null hypothesis was rejected when it was actually true.
A Type I error, because the null hypothesis was retained when it was actually false.
A Type II error, because the null hypothesis was rejected when it was actually true.
A Type II error, because the null hypothesis was retained when it was actually false.
644 exam-style questions on OCR A Level Psychology Research methods and techniques. Each one has a worked solution and a mark scheme showing where the marks go.