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This question assesses learners' basic knowledge of a one-way ANOVA and ability to interpret typical software output.

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A study was conducted to investigate any effect of alcohol consumption on the time taken to complete a cognitive task (involving mental arithmetic). There were three groups of subjects; Group A had no alcohol, Group B had two units over 1 hour and Group C had 4 units over 1 hour. The following table reports the responses as the times (in seconds) taken to complete the task:

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Group A (0 units){r1[0]}{r1[1]}{r1[2]}{r1[3]}{r1[4]}{r1[5]}
Group B (2 units){r2[0]}{r2[1]}{r2[2]}{r2[3]}{r2[4]}{r2[5]}
Group C (4 units){r3[0]}{r3[1]}{r3[2]}{r3[3]}{r3[4]}{r3[5]}
\n

Complete the sections below to test and evaluate the null hypothesis that alcohol consumption does not affect the mean time taken to complete the task.

\n

 

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Revise ANOVA, e.g., Section 7.5 of OpenIntro Statistics (4th edition).

\n

The p-value can be calculated from the F value using Excel's F.DIST.RT function.

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Fill in the gaps in this table of descriptive statistics:

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
 $\\overline{x}_i$$SD_i$$n_i$
Group A[[0]][[1]]6
Group B[[2]][[3]]6
Group C[[4]][[5]]6
   $N=18$
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Fill in the gaps in the ANOVA table:

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
dfSum SqMean SqF
alcohol[[0]][[1]][[2]][[3]]
Residuals[[4]][[5]]$\\var{mrs}$-
Total[[6]]$\\var{tss}$--
\n

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"mustBeReduced": false, "mustBeReducedPC": 0, "displayAnswer": "", "showFractionHint": true, "notationStyles": ["plain", "en", "si-en"], "correctAnswerStyle": "plain"}, {"type": "numberentry", "useCustomName": false, "customName": "", "marks": "0.5", "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "minValue": "n-1", "maxValue": "n-1", "correctAnswerFraction": false, "allowFractions": false, "mustBeReduced": false, "mustBeReducedPC": 0, "displayAnswer": "", "showFractionHint": true, "notationStyles": ["plain", "en", "si-en"], "correctAnswerStyle": "plain"}], "sortAnswers": false}, {"type": "1_n_2", "useCustomName": false, "customName": "", "marks": 0, "scripts": {}, "customMarkingAlgorithm": "", 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What is the correct range for the $p$ value?

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$p$ less than $0.1\\%$

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$p$ lies between $0.1\\%$ and $1\\%$

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$p$ lies between $1 \\%$ and $5\\%$

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$p$ lies between $5 \\%$ and $10\\%$

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$p$ is greater than $10\\%$

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What is the strength of evidence against the null hypothesis that the mean times taken are the same for the three groups?

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What is the correct decision based on the ANOVA analysis?

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