Concept explainers
Using the model fit to the data of Exercise 11.8, construct a 95% confidence interval for the
11.8 Laboratory experiments designed to measure LC50 (lethal concentration killing 50% of the test species) values for the effect of certain toxicants on fish are run by two different methods. One method has water continuously flowing through laboratory tanks, and the other method has static water conditions. For purposes of establishing criteria for toxicants, the Environmental Protection Agency (EPA) wants to adjust all results to the flow-through condition. Thus, a model is needed to relate the two types of observations. Observations on toxicants examined under both static and flow-through conditions yielded the data in the accompanying table (measurements in parts per million, ppm). Fit the model
- a What interpretation can you give to the results?
- b Estimate the flow-through value for a toxicant with an LC50 static value of x = 12 ppm.
11.18
- a Calculate SSE and S2 for Exercise 11.8.
- b Refer to Exercise 11.8. Code the x-values in a convenient manner and fit a simple linear model to the LC50 measurements presented there. Compute SSE and compare your answer to the result of part (a).
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Mathematical Statistics with Applications
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