Chapter 7 - Video tutorials index

Video tutorial 7.1 Principles of hypothesis testing

Similar to Recording 6.1 for confidence intervals, this video explains the mechanics of hypothesis testing. Formation of the hypotheses is discussed along with the concept of a test statistic and its associated distribution. Specification of a significance level, α, is covered and its role in determining critical values in order to define an appropriate critical/rejection region. Interpretation of how to draw conclusions from comparing an observed test statistic value with the critical values is also covered.  Duration: 40 minutes 47 seconds.

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Video tutorial 7.2 Test statistic scenarios

This recording is the hypothesis testing equivalent of Recordings 6.2 and 6.3. All the test statistics associated with testing (i) single population means (ii) differences between population means (iii) single population proportions and (iv) differences between population proportions are covered. Just as with confidence intervals, unknown population variances must be treated appropriately when testing means.  Duration: 23 minutes 23 seconds.

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Video tutorial 7.3 Testing a single population mean

Question: It may be assumed that the length of nails produced by a particular machine is a normally distributed random variable, with standard deviation 0.02 cm. The lengths of a sample of 5 nails are 1.14, 1.15, 1.14, 1.12 and 1.16 cm. Test, at the 5% significance level, the hypothesis that the machine produces nails with a mean length 1.12 cm.  Duration: 9 minutes 51 seconds.

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Video tutorial 7.4 Testing the difference between population means

Question: The mean reaction times, in hundredths of a second, of two groups of subjects to a flashing-light stimulus are measured. The first group, denoted by subscript 1, comprised individuals who were new to the experiment while the subjects in the second group, denoted by subscript 2, had previously taken part. Summary statistics for the two samples are given below.

1 = 3.0	s21 = 0.064	n1 = 10
2 = 2.7	s22 = 0.031	n2 = 8

Test if experience has had an effect on the mean response time.  Duration: 15 minutes 25 seconds.

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Video tutorial 7.5 Testing a single population proportion

Question: An accounting firm wishes to test the claim that no more than 1% of a large number of transactions contains errors. In order to test this claim, they examine a random sample of 144 transactions and find that exactly 3 of these are in error. What conclusion should the firm draw? Duration: 11 minutes 0 seconds.

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Video tutorial 7.6 Testing the difference between population proportions

Question: A market research company has conducted a survey of adults in two large towns, either side of an international border, in order to judge attitudes towards a controversial internationally broadcast celebrity television programme. The following table shows some of the information obtained by the survey:

	Town A	Town B
Sample size	40	40
Sample number approving of the programme	24	22

Conduct a formal hypothesis test, at the 5% significance level, of the claim that the population proportions approving the programme in the two towns are equal.  Duration: 12 minutes 11 seconds.

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