Chapter 11: Problem 21
If the sample size for each treatment is \(n_{t}\) and if \(s^{2}\) is based on \(12 d f\), find \(\omega\) in these cases: a. \(\alpha=.05, k=4, n_{t}=5\) b. \(\alpha=.01, k=6, n_{t}=8\)
Chapter 11: Problem 21
If the sample size for each treatment is \(n_{t}\) and if \(s^{2}\) is based on \(12 d f\), find \(\omega\) in these cases: a. \(\alpha=.05, k=4, n_{t}=5\) b. \(\alpha=.01, k=6, n_{t}=8\)
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Get started for freeSuppose you were to conduct a two-factor factorial experiment, factor \(\mathrm{A}\) at four levels and factor \(\mathrm{B}\) at two levels, with \(r\) replications per treatment. a. How many treatments are involved in the experiment? b. How many observations are involved? c. List the sources of variation and their respective degrees of freedom.
An experiment was conducted to compare the effects of four different chemicals, \(\mathrm{A}, \mathrm{B}, \mathrm{C},\) and \(\mathrm{D},\) in producing water resistance in textiles. A strip of material, randomly selected from a bolt, was cut into four pieces, and the four pieces were randomly assigned to receive one of the four chemicals, \(\mathrm{A}, \mathrm{B}, \mathrm{C},\) or \(\mathrm{D} .\) This process was replicated three times, thus producing a randomized block design. The design, with moistureresistance measurements, is as shown in the figure (low readings indicate low moisture penetration). Analyze the experiment using a method appropriate for this randomized block design. Identify the blocks and treatments, and investigate any possible differences in treatment means. If any differences exist, use an appropriate method to specifically identify where the differences lie. What are the practical implications for the chemical producers? Has blocking been effective in this experiment? Present your results in the form of a report. $$$ \begin{aligned} &\text { Blocks (bolt samples) }\\\ &\begin{array}{|c|c|c|} \hline 1 & 2 & 3 \\ \hline \mathrm{C} & \mathrm{D} & \mathrm{B} \\ 9.9 & 13.4 & 12.7 \\ \mathrm{A} & \mathrm{B} & \mathrm{D} \\ 10.1 & 12.9 & 12.9 \\ \mathrm{B} & \mathrm{A} & \mathrm{C} \\ 11.4 & 12.2 & 11.4 \\ \mathrm{D}_{2} & \mathrm{C} & \mathrm{A} \\ 12.1 & 12.3 & 11.9 \end{array} \end{aligned} $$
Water samples were taken at four different locations in a river to determine whether the quantity of dissolved oxygen, a measure of water pollution, varied from one location to another. Locations 1 and 2 were selected above an industrial plant, one near the shore and the other in midstream; location 3 was adjacent to the industrial water discharge for the plant; and location 4 was slightly downriver in midstream. Five water specimens were randomly selected at each location, but one specimen, corresponding to location \(4,\) was lost in the laboratory. The data and a MINITAB analysis of variance computer printout are provided here (the greater the pollution, the lower the dissolved oxygen readings). $$ \begin{array}{llllll} \text { Location } && {\text { Mean Dissolved }} {\text { Oxygen Content }} \\\ \hline 1 &&& 5.9 & 6.1 & 6.3 & 6.1 & 6.0 \\ 2 &&& 6.3 & 6.6 & 6.4 & 6.4 & 6.5 \\ 3 &&& 4.8 & 4.3 & 5.0 & 4.7 & 5.1 \\ 4 &&& 6.0 & 6.2 & 6.1 & 5.8 & \end{array} $$ a. Do the data provide sufficient evidence to indicate a difference in the mean dissolved oxygen contents for the four locations? b. Compare the mean dissolved oxygen content in midstream above the plant with the mean content adjacent to the plant (location 2 versus location 3 ). Use a \(95 \%\) confidence interval.
A chain of jewelry stores conducted an experiment to investigate the effect of price and location on the demand for its diamonds. Six small-town stores were selected for the study, as well as six stores located in large suburban malls. Two stores in each of these locations were assigned to each of three item percentage markups. The percentage gain (or loss) in sales for each store was recorded at the end of 1 month. The data are shown in the accompanying table. $$ \begin{array}{lrrr} {\text { Markup }} \\ \hline \text { Location } & 1 & 2 & 3 \\ \hline \text { Small towns } & 10 & -3 & -10 \\ & 4 & 7 & -24 \\ \hline \text { Suburban malls } & 14 & 8 & -4 \\ & 18 & 3 & 3 \end{array} $$ a. Do the data provide sufficient evidence to indicate an interaction between markup and location? Test using \(\alpha=.05 .\) b. What are the practical implications of your test in part a? c. Draw a line graph similar to Figure 11.11 to help visualize the results of this experiment. Summarize the results. d. Find a \(95 \%\) confidence interval for the difference in mean change in sales for stores in small towns versus those in suburban malls if the stores are using price markup \(3 .\)
An experiment was conducted to compare the effectiveness of three training programs, \(\mathrm{A}, \mathrm{B},\) and \(\mathrm{C},\) in training assemblers of a piece of electronic equipment. Fifteen employees were randomly assigned, five each, to the three programs. After completion of the courses, each person was required to assemble four pieces of the equipment, and the average length of time required to complete the assembly was recorded. Several of the employees resigned during the course of the program; the remainder were evaluated, producing the data shown in the accompanying table. Use the MINITAB printout to answer the questions. $$ \begin{array}{lllll} \text { Training Program } & {\text { Average Assembly Time (min) }} \\ \hline \text { A } && 59 & 64 & 57 & 62 \\ \text { B } && 52 & 58 & 54 & \\ \text { C } && 58 & 65 & 71 & 63 & 64 \end{array} $$ a. Do the data provide sufficient evidence to indicate a difference in mean assembly times for people trained by the three programs? Give the \(p\) -value for the test and interpret its value. b. Find a \(99 \%\) confidence interval for the difference in mean assembly times between persons trained by programs \(\mathrm{A}\) and \(\mathrm{B}\) c. Find a \(99 \%\) confidence interval for the mean assembly times for persons trained in program A. d. Do you think the data will satisfy (approximately) the assumption that they have been selected from normal populations? Why?
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