Chi-squared test of independence

A question is this type if and only if it involves testing whether two categorical variables are independent using a contingency table and chi-squared test.

8 questions · Standard +0.1

5.06a Chi-squared: contingency tables
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Edexcel S3 2023 January Q3
9 marks Moderate -0.8
3 A mobile phone company offers an insurance policy to its customers when they purchase a mobile phone. The company conducted a survey on the age of the customers and whether or not claims were made. A random sample of 1200 customers from this company was investigated for 2020 and the results are shown in the table below.
Claim made in 2020No claim made in 2020Total
\multirow{3}{*}{Age}17-20 years24176200
21-50 years48652700
51 years and over14286300
Total8611141200
The data are to be used to determine whether or not making a claim is independent of age.
  1. Calculate the expected frequencies for the age group 51 years and over that
    1. made a claim in 2020
    2. did not make a claim in 2020 The 4 classes of customers aged between 17 and 50 give a value of \(\sum \frac { ( O - E ) ^ { 2 } } { E } = 7.123\) correct to 3 decimal places.
  2. Test, at the \(1 \%\) level of significance, whether or not making a claim is independent of age. Show your working clearly, stating your hypotheses, the degrees of freedom, the test statistic and the critical value used.
Edexcel S3 2023 June Q2
10 marks Moderate -0.3
  1. A business accepts cash, bank cards or mobile apps as payment methods.
The manager wishes to test whether or not there is an association between the payment amount and the payment method used. The manager takes a random sample of 240 payments and records the payment amount and the payment method used. The manager's results are shown in the table.
\multirow{2}{*}{}Payment amount
Under £50£50 to £150Over £150
\multirow{3}{*}{Payment method}Cash231918
Bank card213231
Mobile app163941
Using these results,
  1. calculate the expected frequencies for the payment amount under \(\pounds 50\) that
    1. use cash
    2. use a bank card
    3. use a mobile app Given that for the other 6 classes \(\sum \frac { ( O - E ) ^ { 2 } } { E } = 2.4048\) to 4 decimal places,
  2. test, at the \(5 \%\) level of significance, whether or not there is evidence for an association between the payment amount and the payment method used. You should state the hypotheses, the test statistic, the degrees of freedom and the critical value used for this test.
Edexcel S3 2020 October Q2
9 marks Moderate -0.3
2. A university awards its graduates a degree in one of three categories, Distinction, Merit or Pass. Table 1 shows information about a random sample of 200 graduates from three departments, Arts, Humanities and Sciences. \begin{table}[h]
\cline { 2 - 5 } \multicolumn{1}{c|}{}ArtsHumanitiesSciencesTotal
Distinction22323892
Merit15301358
Pass18151750
Total557768
\captionsetup{labelformat=empty} \caption{Table 1}
\end{table} Xiu wants to carry out a test of independence between the category of degree and the department. Table 2 shows some of the values of \(\frac { ( O - E ) ^ { 2 } } { E }\) for this test. \begin{table}[h]
\cline { 2 - 5 } \multicolumn{1}{c|}{}ArtsHumanitiesSciencesTotal
Distinction0.430.331.442.20
Merit0.062.632.294.98
Pass
\captionsetup{labelformat=empty} \caption{Table 2}
\end{table}
  1. Complete Table 2
  2. Hence, complete Xiu's hypothesis test using a \(5 \%\) level of significance. You should state the hypotheses, the degrees of freedom and the critical value used for this test.
Edexcel FS1 AS 2021 June Q4
7 marks Challenging +1.2
  1. Charlie carried out a survey on the main type of investment people have.
The contingency table below shows the results of a survey of a random sample of people.
\cline { 3 - 5 } \multicolumn{2}{c|}{}Main type of investment
\cline { 3 - 5 } \multicolumn{2}{c|}{}BondsCashStocks
\multirow{2}{*}{Age}\(25 - 44\)\(a\)\(b - e\)\(e\)
\cline { 2 - 5 }\(45 - 75\)\(c\)\(d - 59\)59
  1. Find an expression, in terms of \(a , b , c\) and \(d\), for the difference between the observed and the expected value \(( O - E )\) for the group whose main type of investment is Bonds and are aged 45-75
    Express your answer as a single fraction in its simplest form. Given that \(\sum \frac { ( O - E ) ^ { 2 } } { E } = 9.62\) for this information,
  2. test, at the \(5 \%\) level of significance, whether or not there is evidence of an association between the age of a person and the main type of investment they have. You should state your hypotheses, critical value and conclusion clearly. You may assume that no cells need to be combined.
Edexcel S3 2015 June Q5
12 marks Standard +0.3
A Head of Department at a large university believes that gender is independent of the grade obtained by students on a Business Foundation course. A random sample was taken of 200 male students and 160 female students who had studied the course. The results are summarised below.
MaleFemale
Distinction18.5\%27.5\%
Merit63.5\%60.0\%
Unsatisfactory18.0\%12.5\%
Stating your hypotheses clearly, test the Head of Department's belief using a 5\% level of significance. Show your working clearly. [12]
Edexcel S3 Q5
11 marks Standard +0.3
The manager of a leisure centre collected data on the usage of the facilities in the centre by its members. A random sample from her records is summarised below.
FacilityMaleFemale
Pool4068
Jacuzzi2633
Gym5231
Making your method clear, test whether or not there is any evidence of an association between gender and use of the club facilities. State your hypotheses clearly and use a 5\% level of significance. [11]
Edexcel S3 2005 June Q3
Standard +0.3
A researcher carried out a survey of three treatments for a fruit tree disease. The contingency table below shows the results of a survey of a random sample of 60 diseased trees.
No actionRemove diseased branchesSpray with chemicals
Tree died within 1 year1056
Tree survived for 1–4 years597
Tree survived beyond 4 years567
Test, at the 5\% level of significance, whether or not there is any association between the treatment of the trees and their survival. State your hypotheses and conclusion clearly. (Total 11 marks)
OCR MEI S2 2007 January Q4
18 marks Standard +0.3
Two educational researchers are investigating the relationship between personal ambitions and home location of students. The researchers classify students into those whose main personal ambition is good academic results and those who have some other ambition. A random sample of 480 students is selected.
  1. One researcher summarises the data as follows.
    \multirow{2}{*}{Observed}Home location
    \cline{2-3}CityNon-city
    \multirow{2}{*}{Ambition}Good results102147
    \cline{2-3}Other75156
    Carry out a test at the 5\% significance level to examine whether there is any association between home location and ambition. State carefully your null and alternative hypotheses. Your working should include a table showing the contributions of each cell to the test statistic. [9]
  2. The other researcher summarises the same data in a different way as follows.
    \multirow{2}{*}{Observed}Home location
    \cline{2-4}CityTownCountry
    \multirow{2}{*}{Ambition}Good results1028364
    \cline{2-4}Other756492
    1. Calculate the expected frequencies for both 'Country' cells. [2]
    2. The test statistic for these data is 10.94. Carry out a test at the 5\% level based on this table, using the same hypotheses as in part (i). [3]
    3. The table below gives the contribution of each cell to the test statistic. Discuss briefly how personal ambitions are related to home location. [2]
      \multirow{2}{*}{
      Contribution to the
      test statistic
      }
      Home location
      \cline{2-4}CityTownCountry
      \multirow{2}{*}{Ambition}Good results1.1290.5963.540
      \cline{2-4}Other1.2170.6433.816
  3. Comment briefly on whether the analysis in part (ii) means that the conclusion in part (i) is invalid. [2]