/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 52 Will I bomb the final? We expect... [FREE SOLUTION] | 91Ó°ÊÓ

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Will I bomb the final? We expect that students who do well on the midterm exam in a course will usually also do well on the final exam. Gary Smith of Pomona College looked at the exam scores of all 346 students who took his statistics class over a 10-year period." The least-squares line for predict- ing final-exam score from midterm-exam score was \(\hat{y}=46.6+0.41 x\) . Octavio scores 10 points above the class mean on the midterm. How many points above the class mean do you predict that he will score on the final? (This is an example of the phenomenon that gave "regression" its name: students who do well on the midterm will on the average do less well, but still above average, on the final.)

Short Answer

Expert verified
Octavio is predicted to score 4.1 points above the class mean on the final exam.

Step by step solution

01

Understand the Regression Equation

The given least-squares regression line is \(\hat{y} = 46.6 + 0.41x\). Here, \(\hat{y}\) is the predicted final exam score, and \(x\) is the midterm exam score.
02

Interpret the Regression Coefficient

The coefficient \(0.41\) in the regression equation implies that for each additional point a student scores above the mean on the midterm, we predict their final exam score to increase by 0.41 points.
03

Calculate Prediction for Octavio

Octavio scores 10 points above the class mean on the midterm. Thus, we use the regression coefficient to determine Octavio's predicted final score. Multiply the difference by the coefficient: \(0.41 \times 10 = 4.1\).
04

Conclusion

Since Octavio scores 10 points above the mean on the midterm, we predict that he will score 4.1 points above the mean on the final exam.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Least-Squares Regression
Least-squares regression is a fundamental concept in statistics used to find the best-fitting line through a set of data points. Essentially, it helps minimize the differences between the observed values and the values predicted by the linear model. This process involves adjusting the line to where the sum of the squares of these differences (called residuals) is as small as possible. In practical terms, least-squares regression is a tool
- to make predictions, - to understand relationships between variables, and - to analyze trends. For students learning statistics, mastering least-squares regression is critical. It serves as the basis for more complex statistical models and provides insights into how one variable can be used to predict another.
Regression Coefficient
The regression coefficient in a least-squares regression equation denotes the expected change in the dependent variable, given a one-unit change in the independent variable. In the formula \[\hat{y} = a + bx\]\(b\) is the regression coefficient. For instance, in the equation provided, \[0.41\] acts as the regression coefficient. It indicates that for each additional point a student scores on the midterm, their predicted final exam score increases by 0.41 points. This coefficient is crucial because it tells us the strength and direction of the relationship between variables.
- Positive coefficients suggest a positive correlation, where an increase in one variable leads to an increase in the other. - Negative coefficients suggest a negative correlation, where an increase in one variable leads to a decrease in the other.
Understanding the regression coefficient allows educators and students to interpret the impact of changes in one variable on another, enhancing predictive insights.
Predictive Modeling
Predictive modeling utilizes statistical techniques to create models that can predict future outcomes based on current or historical data. In the context of the original exercise, predictive modeling helps forecast a student's final exam score based on their midterm performance. This method relies on the least-squares regression line to make reliable predictions. By employing predictive modeling:
- Educators can identify students who might need additional support. - Students can gauge their potential performance. - Institutions can improve overall educational strategies. Continuous data monitoring and applying predictive models provide valuable foresight into potential academic outcomes, supporting better decision-making and planning in educational settings.
Statistical Analysis
Statistical analysis refers to a comprehensive collection of methods used to collect, review, analyze, and draw conclusions from data. This process involves not only designing surveys and experiments but also interpreting the results. In the exercise, the statistical analysis was used to derive the least-squares regression equation, highlighting the relationship between midterm and final exam scores. Effective statistical analysis - ensures accuracy in conclusions, - unveils trends and correlations, and - enhances understanding of data patterns. Moreover, it provides a foundation for making informed educational predictions and decisions. By regularly applying statistical analyses, educators can detect areas of improvement and steer their students towards better learning outcomes.

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Most popular questions from this chapter

Beer and blood alcohol The example on page 182 describes a study in which adults drank different amounts of beer. The response variable was their blood alcohol content (BAC). BAC for the same amount of beer might depend on other facts about the subjects. Name two other variables that could ac- count for the fact that \(r^{2}=0.80\) .

Correlation blunders Fach of the following statements contains an error. Explain what's wrong in each case. (a) There is a high correlation between the gender of American workers and their income." (b) "We found a high correlation \((r=1.09)\) between students' ratings of faculty teaching and ratings made by other faculty members." (c) The correlation between planting rate and yield of corn was found to be \(r=0.23\) bushel."

IQ and reading scores Data on the 1\(Q\) test scores and reading test scores for a group of fifth-grade children give the following regression line: predicted reading score \(=-33.4+0.882(1 Q \text { score). }\) (a) What's the slope of this line? Interpret this value in context. (b) What's the intercept? Explain why the value of the intercept is not statistically meaningful. (c) Find the predicted reading scores for two children with IQ scores of 90 and 130 , respectively.

The stock market Some people think that the behavior of the stock market in January predicts its behavior for the rest of the year. Take the explanatory variable \(x\) to be the percent change in a stock market index in January and the response variable \(y\) to be the change in the index for the entire year. We expect a positive correlation between \(x\) and \(y\) because the change during January contributes to the full year's change. Calculation from data for an 18 -year period gives $$ \begin{array}{c}{\overline{x}=1.75 \% \quad s_{x}=5.36 \% \quad \overline{y}=9.07 \%} \\ {s_{y}=15.35 \% \quad r=0.596}\end{array} $$ (a) Find the equation of the least-squares line for predicting full-year change from January change. Show your work. (b) The mean change in January is \(\overline{x}=1.75 \%\) . Use your regression line to predict the change in the index in a year in which the index rises 1.75\(\%\) in January. Why could you have given this result (up to roundoff error) without doing the calculation?

IQ and grades Exercise 3 (page 158\()\) included the plot shown below of school grade point average \((\mathrm{GPA})\) against 1\(Q\) test score for 78 seventh-grade students. (GPA was recorded on a 12 -point scale with \(\mathrm{A}+=12, \mathrm{A}=11, \mathrm{A}-=10, \mathrm{B}+=9, \ldots, \mathrm{D}-=1\) and \(\mathrm{F}=0 .\) . Calculation shows that the mean and standard deviation of the 1 \(\mathrm{Q}\) scores are \(\overline{x}=108.9\) and \(s_{x}=13.17 .\) For the GPAs, these values are \(\overline{y}=\) 7.447 and \(s_{y}=2.10 .\) The correlation between 1 \(\mathrm{Q}\) and GPA is \(r=0.6337 .\) (a) Find the equation of the least-squares line for predicting GPA from 1\(Q\) . Show your work. (b) What percent of the observed variation in these students' GPAs can be explained by the linear relationship between GPA and IQ? (c) One student has an IQ of 103 but a very low GPA of 0.53 . Find and interpret the residual for this student.

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