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LSD and Tukey yardsticks on three treatments. Also one-way Anova test on same set of data.
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\nSource | \ndf | \nSS | \nMS | \nVR | \n
---|---|---|---|---|
Between Treatments | \n$\\var{dfbt}$ | \n[[0]] | \n$\\var{mbt}$ | \n$\\var{vr}$ | \n
Residual | \n[[1]] | \n$\\var{rss}$ | \n$\\var{mrs}$ | \n- | \n
Total | \n[[2]] | \n[[3]] | \n- | \n- | \n
$\\sqrt{RMS} = \\var{sqrms}$, to 2 decimal places. This will be used to calculate the LSD and Tukey yardstick values later.
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\nGiven the value of $VR$ in the table above, find the range for the $p$ value by using the critical values of $F_{2,15}$ (one-sided) below.
\n$10\\%$ | \n$5\\%$ | \n$1\\%$ | \n$0.1\\%$ | \n
$2.7$ | \n$3.68$ | \n$6.36$ | \n$11.34$ | \n
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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\n\n | $\\overline{x}_i$ | \n
Group 1 | \n{m1} | \n
---|---|
Group 2 | \n{m2} | \n
Group 3 | \n{m3} | \n
Given $q_{t,\\nu}(\\alpha) =3.67$, $t_{\\nu}(\\alpha) =2.131$ and the value for $\\sqrt{RMS}$ above, find the LSD and Tukey yardsticks from the data.
LSD= [[0]] (to 2 decimal places)
\nTukey= [[1]] (to 2 decimal places)
\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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\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
", "advice": "
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