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LSD and Tukey yardsticks on three treatments. Also one-way Anova test on same set of data.
", "licence": "Creative Commons Attribution 4.0 International"}, "statement": "The following data arose in a comparison of the effects of hydration on the time taken (in minutes) to complete a set of exercises. There were three groups of subjects; group 1 (fully hydrated), group 2 (partially hydrated) and group 3 (dehydrated).
\nGroup 1 (fully hydrated) | \n$\\var{r1[0]}$ | \n$\\var{r1[1]}$ | \n$\\var{r1[2]}$ | \n$\\var{r1[3]}$ | \n$\\var{r1[4]}$ | \n$\\var{r1[5]}$ | \n
---|---|---|---|---|---|---|
Group 2 (partially hydrated) | \n$\\var{r2[0]}$ | \n$\\var{r2[1]}$ | \n$\\var{r2[2]}$ | \n$\\var{r2[3]}$ | \n$\\var{r2[4]}$ | \n$\\var{r2[5]}$ | \n
Group 3 (dehydrated) | \n$\\var{r3[0]}$ | \n$\\var{r3[1]}$ | \n$\\var{r3[2]}$ | \n$\\var{r3[3]}$ | \n$\\var{r3[4]}$ | \n$\\var{r3[5]}$ | \n
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Using the Yardsticks
\nThe mean values for each group are:
\n\n | $\\overline{x}_i$ | \n
Group 1 | \n$\\var{m1}$ | \n
---|---|
Group 2 | \n$\\var{m2}$ | \n
Group 3 | \n$\\var{m3}$ | \n
The differences between the mean values for the groups are:
\nBetween $1$ and $2=\\;|\\var{m1}-\\var{m2}|=\\var{abs(m1-m2)}$
\nBetween $2$ and $3=\\;|\\var{m2}-\\var{m3}|=\\var{abs(m2-m3)}$
\nBetween $1$ and $3=\\;|\\var{m1}-\\var{m3}|=\\var{abs(m1-m3)}$
\nWe compare these differences with the LSD and Tukey yardsticks:
\nLSD yardstick = $2.131\\times\\var{sqrms}\\times\\sqrt{2/\\var{n1}}=\\var{lsd}$ to 2 decimal places, where $\\var{sqrms}$ is the value of $\\sqrt{RMS}$ found above.
\nTukey yardstick = $3.67\\times\\var{sqrms}\\times\\sqrt{1/\\var{n1}}=\\var{tukey}$ to 2 decimal places.
\nIf the difference of the means:
\n\n
Hence we have the following for the groups:
\nPairs of Groups | \nDefinite Significant Difference | \nPossible Significant Difference | \nNo Significant Difference | \n
---|---|---|---|
Means of Groups 1 and 2 | \n{yn[0][0]} | \n{yn[0][1]} | \n{yn[0][2]} | \n
Means of Groups 2 and 3 | \n{yn[1][0]} | \n{yn[1][1]} | \n{yn[1][2]} | \n
Means of Groups 1 and 3 | \n{yn[2][0]} | \n{yn[2][1]} | \n{yn[2][2]} | \n
You are given the following ANOVA table for this data:
\nSource | df | SS | MS | VR |
---|---|---|---|---|
Between Treatments | \n$\\var{dfbt}$ | \n$\\var{btss}$ | \n$\\var{mbt}$ | \n$\\var{vr}$ | \n
Residual | \n$\\var{dfrs}$ | \n$\\var{rss}$ | \n$\\var{mrs}$ | \n- | \n
Total | \n$\\var{n-1}$ | \n$\\var{tss}$ | \n- | \n- | \n
\n
Input $\\sqrt{RMS}$ here: [[0]] to 2 decimal places.
\n\n
This will be used to calculate the LSD and Tukey yardstick values later.
\n \n ", "gaps": [{"type": "numberentry", "useCustomName": false, "customName": "", "marks": 1, "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "minValue": "sqrms-tol", "maxValue": "sqrms+tol", "correctAnswerFraction": false, "allowFractions": false, "mustBeReduced": false, "mustBeReducedPC": 0, "showFractionHint": true, "notationStyles": ["plain", "en", "si-en"], "correctAnswerStyle": "plain"}], "sortAnswers": false}, {"type": "1_n_2", "useCustomName": false, "customName": "", "marks": 0, "scripts": {}, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "showCorrectAnswer": true, "showFeedbackIcon": true, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "nextParts": [], "suggestGoingBack": false, "adaptiveMarkingPenalty": 0, "exploreObjective": null, "prompt": "\nUsing ANOVA
\nUsing the $VR$ value given in the table and one-way ANOVA, 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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\nFill in this table with the appropriate values for the mean values of the groups, all decimals to 2 decimal places:
\n\n | $\\overline{x}_i$ | \n
Group 1 | \n[[0]] | \n
---|---|
Group 2 | \n[[1]] | \n
Group 3 | \n[[2]] | \n
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Now find the LSD and Tukey yardsticks from the above data. Use the value to 2 decimal places you found for $\\sqrt{RMS}$:
\nLSD= [[0]]
\nTukey= [[1]]
\nUsing these yardsticks fill in the following table indicating if there is a possible or definite significant difference between the pairs of groups mean times in undertaking the tasks:
\n[[2]]
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