Questions and Answers of Design And Analysis Of Experiments

An article in Environment International (Vol. 18, No. 4, 1992) describes an experiment in which the amount of radon released in showers was investigated. Radon-enriched water was used in the
An article in the ACI Materials Journal (Vol. 84,1987, pp. 213-216) describes several experiments investigating the rodding of concrete to remove entrapped air. A 3-inch × 6-inch cylinder was used,
Reconsider the experiment from Problem 3-6. Analyze the residuals and draw conclusions about model adequacy.Problem 3-6.A manufacturer of television sets is interested in the effect on tube
A manufacturer of television sets is interested in the effect on tube conductivity of four different types of coating for color picture tubes. The following conductivity data are obtained:(a) Is
Rework part (d) of Problem 3-4 using the Fisher LSD method. What conclusions can you draw? Explain carefully how you modified the technique to account for unequal sample sizes.Problem 3-4An
An experiment was run to determine whether four specific firing temperatures affect me density of a certain type of brick. The experiment led to the following data: (a) Does the firing
Reconsider the experiment in Problem 3-1. Find a 95 percent confidence interval on the mean tensile strength of the portland cement produced by each of the four mixing techniques. Also find a 95
(a) Rework part (b) of Problem 3-1 using Duncan's multiple range test with α = 0.05. Does this make any difference in your conclusions?(b) Rework part (b) of Problem 3-1 using Tukey's test with α =
The tensile strength of portland cement is being studied. Four different mixing techniques can be used economically. The following data have been collected: (a) Test the hypothesis that mixing
Construct a data set for which the paired t-test statistic is very large, but for which the usual two-sample or pooled t-test statistic is small. In general, describe how you created the data. Does
Develop an equation for finding a 100(1 – α) percent confidence interval on the difference in the means of two normal distributions where σ21 ≠ σ22. Apply your equation to the portland cement
Develop Equation 2-50 for a 100(1 – α) percent confidence interval for the ratio σ21/σ21 where σ21 and σ22 are the variances of two normal distributions.Equation 2-50 Fa/2,n2-11-1 F1
Develop Equation 2-46 for a 100(1 – α) percent confidence interval for the variance of a normal distribution.Equation 2-46 (п — 1)52 (п — 1)5? < o? < ,2 2 Xi-(a/2).n-1
Suppose we are testing where σ21 and σ22 are known. Our sampling resources are constrained such that n1 + n2 = N. How should we allocate the N observations between the two populations to
Two popular pain medications are being compared on the basis of the speed of absorption by the body. Specifically, tablet 1 is claimed to be absorbed twice as fast as tablet 2. Assume that σ21 and
In semiconductor manufacturing wet chemical etching is often used to remove silicon from the backs of wafers prior to metalization. The etch rate is an important characteristic of this process. Two
Refer to the data in Problem 2-17. Do the data support a claim that the mean deflection temperature under load for formulation 1 exceeds that of formulation 2 by at least 3°F?Problem 2-17.The
The deflection temperature under load for two different formulations of ABS plastic pipe is being studied. Two samples of 12 observations each are prepared using each formulation and the deflection
An article in the Journal of Swain Analysis (vol. 18, no. 2, 1983) compares several pro-cedures for predicting the shear strength for steel plate girders. Data for nine girders in the form of the
The diameter of a ball bearing was measured by 12 inspectors, each using two different kinds of calipers. The results were (a) Is there a significant difference between the means of the
Twenty observations on etch uniformity on silicon wafers are taken during a qualification experiment for a plasma etcher. The data are as follows: (a) Construct a 95 percent confidence interval
A new filtering device is installed in a chemical unit. Before its installation, a random sample yielded the following information about the percentage of impurity: y̅1 = 12.5, S21 = 101.17, and n1
An article in Solid State Technology, "Orthogonal Design for Process Optimization and Its Application to Plasma Etching" by G. Z. Yin and D. W. Jillie (May, 1987) describes an experiment to determine
The following are the burning times of chemical flares of two different formulations. The design engineers are interested in both the mean and variance of the burning times. (a) Test the
Two types of plastic are suitable for use by an electronic calculator manufacturer. The breaking strength of this plastic is important. It is known that σ1, = σ2 = 1.0 psi. From random samples of
Two machines are used for filling plastic bottles with a net volume of 16.0 ounces. The filling processes can be assumed to be normal, with standard deviations of σ1 = 0.015 and σ2 = 0.018. The
Reconsider the repair time data in Problem 2-7. Can repair time, in your opinion, be adequately modeled by a normal distribution?Problem 2-7The time to repair an electronic instrument is a normally
The time to repair an electronic instrument is a normally distributed random variable measured in hours. The repair times for 16 such instruments chosen at random are as follows: (a) You wish to
Consider the shelf life data in Problem 2-5. Can shelf life be described or modeled adequately by a normal distribution? What effect would violation of this assumption have on the test procedure you
The shelf life of a carbonated beverage is of interest. Ten bottles are randomly selected and tested, and the following results are obtained:Days108138124163124159106134115139(a) We would like to
A normally distributed random variable has an unknown mean p, and a known variance σ2 = 9. Find the sample size required to construct a 95 percent confidence interval on the mean that has total
The diameters of steel shafts produced by a certain manufacturing process should have a mean diameter of 0.255 inches. The diameter is known to have a standard deviation of σ = 0.0001 inch. A random
The viscosity of a liquid detergent is supposed to average 800 centistokes at 25°C. A random sample of 16 batches of detergent is collected, and the average viscosity is 812. Suppose we know that
The breaking strength of a fiber is required to be at least 150 psi. Past experience has indicated that the standard deviation of breaking strength is σ = 3 psi.A random sample of four specimens is
The breaking strength of a fiber is required to be at least 150 psi. Past experience has indicated that the standard deviation of breaking strength is σ = 3 psi.A random sample of four specimens is
The diameters of steel shafts produced by a certain manufacturing process should have a mean diameter of 0.255 inches. The diameter is known to have a standard deviation of σ = 0.0001 inch. A random
The breaking strength of a fiber is required to be at least 150 psi. Past experience has indicated that the standard deviation of breaking strength is σ = 3 psi.A random sample of four specimens is
The breaking strength of a fiber is required to be at least 150 psi. Past experience has indicated that the standard deviation of breaking strength is σ = 3 psi.A random sample of four specimens is
The breaking strength of a fiber is required to be at least 150 psi. Past experience has indicated that the standard deviation of breaking strength is σ = 3 psi.A random sample of four specimens is
The breaking strength of a fiber is required to be at least 150 psi. Past experience has indicated that the standard deviation of breaking strength is σ = 3 psi.A random sample of four specimens is

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