A2 June 2025 Q3

EdexcelCurrent spec12 marksIncludes hypothesis testingChi-Squared Tests

3. A journalist uses a gender equality test on some randomly chosen films.
She believes that whether or not a film passes the test is associated with the period in which the film is first released. Her data is summarised in Table 1.
The journalist decides to test whether the data supports her belief.

Table 1: Observed frequencies

Period →
Test result ↓		1990–19992000–20042005–2013Total
Pass457065180
Fail759055220
Total120160120400

Some of the expected frequencies she calculates are shown in Table 2 below.

Table 2: Expected frequencies

Period →
Test result ↓		1990–19992000–20042005–2013
Pass54
Fail66
(a) Complete Table 2 showing expected frequencies. (2)
(b) Write down hypotheses for a suitable test to assess the journalist’s belief. (1)
(c) Showing your working clearly, test the journalist’s belief using a 5% level of significance.
You should state your critical value and conclusion clearly. (6)

The journalist wants to publish her data and findings.
She decides to publish the data as percentages of pass and fail for each period, as shown in Table 3, rather than as frequencies.

Table 3: Percentages

Period →
Test result ↓		1990–19992000–20042005–2013
Pass (%)37.543.7554.17
Fail (%)62.556.2545.83
Total (%)100100100

The editor suggests carrying out the hypothesis test of the journalist’s belief using the percentages in Table 3.

(d)
(i) Describe the effect this would have on the test statistic, justifying your answer.
(ii) Explain whether or not the journalist should follow her editor’s suggestion. (3)
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