Errata


Last Updated on: Feb 23, 2025 at 08:21:00 AM

meanSEC <- mean(SDS4$times)
meanMIN <- mean(SDS4$times/60)
c(meanSEC, meanMIN)
[1] 7.80 0.13
sdSEC <- sd(SDS4$times)
sdMIN <- sd(SDS4$times/60)
c(sdSEC, sdMIN)
[1] 7.871402 0.131190
CVsec <- meanSEC/sdSEC
CVmin <- meanMIN/sdMIN
c(CVsec, CVmin)
[1] 0.9909289 0.9909289

The code defining the CV has \(\bar{X}/S\) instead of \(S/\bar{X}\). The code should be changed as shown below.

meanSEC <- mean(SDS4$times)
meanMIN <- mean(SDS4$times/60)
c(meanSEC, meanMIN)
[1] 7.80 0.13
sdSEC <- sd(SDS4$times)
sdMIN <- sd(SDS4$times/60)
c(sdSEC, sdMIN)
[1] 7.871402 0.131190
CVsec <- sdSEC/meanSEC
CVmin <- sdMIN/meanMIN
c(CVsec, CVmin)
[1] 1.009154 1.009154

\[P \dot\sim N\left(0.383, \sqrt{\tfrac{(0.383)(0.617)}{250}} = 0.0307 \right)\]

\[\begin{align*} \lambda &= \dfrac{SS_{Hypothesis}}{\sigma^2}\\ &=\frac{\sum_{i=1}^a n_i (\mu_{i\bullet} - \bar{\mu}_{\bullet\bullet})^2}{\sigma^2} \\ &= \dfrac{ 6\cdot(390-405)^2 + 6\cdot(405-405)^2 + 12\cdot(415-405)^2 + 12\cdot(410-405)^2}{14^2} \\ &= \dfrac{2635}{14^2} = 13.3929. \end{align*}\]

In the case with uneven sample sizes, \(\bar{\mu}_{\bullet\bullet} = \frac{(6\cdot390 + 6\cdot405 + 12 \cdot 415 + 12 \cdot 410)}{(6 + 6 + 12 + 12)}= 407.5\), and the 405 should be replaced with 407.5 as shown below.

\[\begin{align*} \lambda &= \dfrac{SS_{Hypothesis}}{\sigma^2}\\ &=\frac{\sum_{i=1}^a n_i (\mu_{i\bullet} - \bar{\mu}_{\bullet\bullet})^2}{\sigma^2} \\ &= \dfrac{ 6\cdot(390-407.5)^2 + 6\cdot(405-407.5)^2 + 12\cdot(415-407.5)^2 + 12\cdot(410-407.5)^2}{14^2} \\ &= \dfrac{2635}{14^2} = 13.3929. \end{align*}\]