Stats chapters 6-9

An exponential relationship exist between the explanatory variable in the response variable in a set of data. The common logarithm of each value of the response variable is taken, in the least squares regression line has an equation of log(ÿ)=7.3-1.5x. Which of the following is closest to the predicted value of the response variable for x=4.8?

1.26

The computer outlet below shows the results of a linear regression analysis for predicting the concentration of zinc, in parts per million (ppm), for the concentration of lead, in ppm, found in fish from a certain river. Which of the following statements is a correct interpretation of the value 19.0 in output?

On average there is a predicted increase of 19.0 ppm in concentration of zinc for every increase of 1 ppm in concentration of lead found in the fish

A researcher in Alaska measured the age (in months) and the weight (in pounds) of a random sample of adolescent moose. When the least-squares regression analysis was performed, the correlation was 0.59. Which of the following is the correct way to label the correlation?

0.59

Dairy farmers are aware there is often a linear relationship between age, in years, of a dairy cow in the amount of milk produced, in gallons per week. The least squares regression line produced from a random sample is milk=40.8-1.1(Age). Based on the model, what is the difference in predicted amounts of milk produce between a cow of five years in a cow of 10 years?

A cow of five years is predicted to produce 5.5 more gallons per week

The scatterplot of student heights, in inches, versus corresponding arm span length, in inches, is shown below. One of the points in the graph is labeled A. If the point labeled A is removed, which of the following statements would be true?

The slope of the least squares regression line increases in the correlation coefficient increases

For a random sample of 20 professional athletes, there is a strong, linear relationship between the number of hours they exercise per week and they're resting heart rate. For the athletes in the sample, those who exercise more hours per week tend to have lower resting heart rates than those who exercise less. Which of the following is a reasonable value for the correlation between the number of hours athletes exercise per week and they're resting heart rate?

-0.87

The table shows several values of X and their corresponding values of Y. Which of the following is the closest to the correlation between X and Y?

0.98

Which of the following is the best description of a positive association between two variables?

As the value of one of the variables increases, the value of the other variable tends to increase

A botanist found a correlation between the length of an Aspenleaf and its surface area to be 0.94. Why does the correlation value of 0.94 not necessarily indicate that a linear model is the most appropriate model for the relationship between length of an aspen leaf and its surface area?

Even with a correlation value of 0.94, it is possible that the relationship could still be better represented by a non-linear model

Which of the following statements about least squares regression analysis is true? I. A point with a large residual is an outlier II. A point with high leverage has a Y value that is not consistent with the other Y values in the set III. The removal of an influential point from the data set could change the value of the correlation coefficient

III only

At a large airport, data were recorded for one month on how many baggage items were unloaded from each flight upon arrival as well as the time required to deliver all the baggage items on the flight to the baggage claim area. The scatterplot of the two variables indicated a strong, positive, linear association between the variables. Which of the following statements is a correct interpretation of the word "strong" in the description of the association?

The actual time required to deliver all the items to the baggage claim area based on the number of items and loaded will be very close to the time predicted by a least-squares model

Clear-cut harvesting of wood from forest creates long periods of time when certain animals cannot use the forest as habitats. Partial cut harvesting is increasingly used to lessen the effects of logging on the animals. The following scatterplot shows the relationship between the density of red squirrels, and squirrels per plot, 2 to 4 years after partial cut harvesting, and the percent of trees that were harvested in each of 11 Forests. Which of the following is the best description of the relationship displayed in the scatterplot?

negative, linear, and strong