Do types of crimes reported on television newscasts

Yaritza Estrada

Yaritza Estrada

Answered question

2022-04-12

Do types of crimes reported on television newscasts differ by the age of the criminals? A researcher uses her dvr to record the local television news for a 2-week period of time. She records the types of crimes and notes the age of the offender. Conduct a chi-square test (α=0.05) of the null hypothesis that televised offense type does not vary by age group of offender.
 Offense type  Young  middle age  older  violent 27103 property 141211 sex 795
Report the obtained chi-square, df, and critical chi-square. Report your findings based on the null hypothesis.

Answer & Explanation

lildeutsch11xq2j

lildeutsch11xq2j

Beginner2022-04-13Added 13 answers

For the given data, the chi-square test for association is appropriate.
Null Hypothesis:
The televised offense type does not vary by age group of the offender.
Alternative Hypothesis:
The televised offense type vary by age group of the offender.
Procedure for calculating chi-square test statistic using MegaStat:
1. Go to MegaStat > Chi-square/Crosstab > Contingency table.
2. Select the input range of the data as “$A$1:$D$4”.
3. In output options, Select expected values, Chi-square and (O-E)^2/E.
4. Click OK
From the MegaStat output, the chi-square test statistic is 11.36 which is given below:
    Young  middle age  older  Total  violent  Observed 2710340   Expected 19.5912.657.7640.00   (O-E)^2/E 2.800.562.926.27  % of chisq 24.7%4.9%25.7%55.2%  property  Observed 14121137   Expected 18.1211.707.1737.00   (O-E)^2/E 0.940.012.042.99   % of chisq 8.3%0.1%18.0%26.3%  sex  Observed 79521   Expected 10.296.644.0721.00   (O-E)^2/E 1.050.840.212.10   % of chisq 9.2%7.4%1.9%18.5%  Total  Observed 48311998   Expected 48.0031.0019.0098.00   (O-E)^2/E 4.791.405.1711.36   % of chisq 42.2%12.3%45.5%100.0% 
From the output,
Chi-square is 11.36.
Degree of freedom is 4.
The critical value is 9.488 using the Excel formula '=CHISQ.INV.RT(0.05,4).
Decision rule:
If p-value α, then reject the null hypothesis. Otherwise, do not reject the null hypothesis.
Here, p-value is 0.0228, which is less than the level of significance (0.05). Thus, reject the null hypothesis. Thus, the televised offense type varies by age group of the offender.

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