A manufacturer of automobile spark plugs has several production facilities sprea

Question

A manufacturer of automobile spark plugs has several production facilities spread across a wide geographical area. The quality control manager at each plant budgets a certain amount of money (QC $, measured in thousands of dollars) for quality control efforts each week (maintenance and calibration of equipment, time spent on process evaluation, etc.). Each manager also determines the percentage of defective spark plugs (% DEF) produced each week. The company's vice president of operations has collected a sample of data to determine the association between these variables. A scatterplot, fitted line, and summary output for a simple regression model are provided:

Which of the following conclusions is an appropriate interpretation of these results? The simple regression model should not be used because the residual plot displays no linear pattern. The simple regression model should not be used because the sign of r2 does not match the sign of the slope b_1 On average, a $1000 increase in the amount of money spent on quality control is estimated to result in a.936% decrease in the percentage of defectives. The model does not appear to explain statistically significant variation in the percentage of defectives being produced. The similar variances condition for a simple regression model appears to be satisfied.

Explanation / Answer

We can use simple regression model because residual plot does not show any specific pattern

r^2 is always positive. Sign of slope and sign of r should match.

R^2 is used to show teh variation in dependent variable explained by independent variable.

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Last option is correct about the model .

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