# Question

Carbon aerosols have been identified as a contributing factor in a number of air quality problems. In a chemical analysis of diesel engine exhaust, x = mass (mg/cm2) and y = elemental carbon (mg/cm2) were recorded (“Comparison of Solvent Extraction and Thermal Optical Carbon Analysis Methods: Application to Diesel Vehicle Exhaust Aerosol” Environmental Science Technology [1984]: 231– 234). The estimated regression line for this data set is y^ = 31 1 .737x. The accompanying table gives the observed x and y values and the corresponding standardized residuals.

a. Construct a standardized residual plot. Are there any unusually large residuals? Do you think that there are any influential observations?

b. Is there any pattern in the standardized residual plot that would indicate that the simple linear regression model is not appropriate?

c. Based on your plot in Part (a), do you think that it is reasonable to assume that the variance of y is the same at each x value? Explain.

a. Construct a standardized residual plot. Are there any unusually large residuals? Do you think that there are any influential observations?

b. Is there any pattern in the standardized residual plot that would indicate that the simple linear regression model is not appropriate?

c. Based on your plot in Part (a), do you think that it is reasonable to assume that the variance of y is the same at each x value? Explain.

## Answer to relevant Questions

An investigation of the relationship between x = traffic flow (thousands of cars per 24 hours) and y 5 lead content of bark on trees near the highway (mg/g dry weight) yielded the accompanying data. A simple linear ...The data of Exercise13. 25, in which x = milk temperature and y = milk pH, yield a. Obtain a 95% confidence interval for a 1 b(40), the mean milk pH when the milk temperature is 408C. b. Calculate a 99% confidence interval ...The shelf life of packaged food depends on many factors. Dry cereal is considered to be a moisturesensitive product (no one likes soggy cereal!) with the shelf life determined primarily by moisture content. In a study of the ...Television is regarded by many as a prime culprit for the difficulty many students have in performing well in school. The article “The Impact of Athletics, Part- Time Employment, and Other Activities on Academic ...a. Explain the difference between the line y = a + bx and the line y^ = a+1 bx. b. Explain the difference between b and b. c. Let x* denote a particular value of the independent variable. Explain the difference between a1 ...Post your question

0