/*! 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 15 The following data are based on ... [FREE SOLUTION] | 91Ó°ÊÓ

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The following data are based on information from the book Life in America's Small Cities (by G. S. Thomas, Prometheus Books). Let \(x\) be the percentage of 16 - to 19 -year-olds not in school and not high school graduates. Let \(y\) be the reported violent crimes per 1000 residents. Six small cities in Arkansas (Blytheville, El Dorado, Hot Springs, Jonesboro, Rogers, and Russellville) reported the following information about \(x\) and \(y\) : $$ \begin{array}{l|llllll} \hline x & 24.2 & 19.0 & 18.2 & 14.9 & 19.0 & 17.5 \\ \hline y & 13.0 & 4.4 & 9.3 & 1.3 & 0.8 & 3.6 \\ \hline \end{array} $$ Complete parts (a) through (e), given \(\Sigma x=112.8, \Sigma y=32.4, \Sigma x^{2}=2167.14\), \(\Sigma y^{2}=290.14, \Sigma x y=665.03\), and \(r \approx 0.764\). (f) If the percentage of 16 - to 19 -year-olds not in school and not graduates reaches \(24 \%\) in a similar city, what is the predicted rate of violent crimes per 1000 residents?

Short Answer

Expert verified
The predicted rate of violent crimes is 11.64 per 1000 residents.

Step by step solution

01

Understand the Regression Equation

The regression line, or line of best fit, is used for making predictions and is given by the formula \( y = mx + c \), where \( m \) is the slope and \( c \) is the y-intercept. To find \( m \) and \( c \), we use statistics from the data points.
02

Calculate the Slope (m)

The formula for the slope \( m \) of the regression line is given by \( m = \frac{n(\Sigma xy) - (\Sigma x)(\Sigma y)}{n(\Sigma x^2) - (\Sigma x)^2} \). Plugging the given values into the formula, we have:\[m = \frac{6(665.03) - (112.8)(32.4)}{6(2167.14) - (112.8)^2}\]Calculating this, we find:\[m = \frac{3990.18 - 3650.72}{13002.84 - 12719.04} = \frac{339.46}{283.8} \approx 1.2\]
03

Calculate the Y-Intercept (c)

The y-intercept \( c \) can be found using the formula:\[ c = \frac{\Sigma y - m \Sigma x}{n} \]Substituting the known values, we have:\[ c = \frac{32.4 - 1.2(112.8)}{6} \]Calculating:\[ c = \frac{32.4 - 135.36}{6} = \frac{-102.96}{6} \approx -17.16 \]
04

Formulate the Regression Equation

The regression equation is now formed using the slope and y-intercept. Thus, the equation is:\[ y = 1.2x - 17.16 \]
05

Predict the Rate of Violent Crimes

To predict the violent crime rate when the percentage of 16- to 19-year-olds not in school and not graduates reaches 24%, substitute \( x = 24 \) into the regression equation:\[ y = 1.2(24) - 17.16 \]Calculating:\[ y = 28.8 - 17.16 = 11.64 \]Thus, the predicted rate of violent crimes per 1000 residents is approximately 11.64.

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Key Concepts

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

Statistics Education
Understanding statistics is vital in today's data-driven world. Statistics offers tools to interpret complex data and uncover patterns and trends. In learning statistics, one essential concept is regression analysis. It involves examining relationships between variables and predicting future trends based on those relationships. For students and professionals alike, mastering this concept can empower them to make informed decisions and forecasts.

Statistics education goes beyond merely learning formulas. It's about grasping the reasoning behind statistical methods and understanding how to apply them effectively. This understanding begins with foundational topics such as mean, median, mode, and variance, which lead up to more advanced topics like correlation and regression. By gaining confidence in these areas, students are better prepared to tackle real-world problems involving data analysis.

It's beneficial to use practical examples and exercises, like the small city data set from Arkansas, to demonstrate how statistics operates in real life. By working through these examples, students see firsthand how theoretical concepts translate into practical applications. They learn not only the calculations needed but also the intuition behind why these calculations matter. This kind of comprehensive understanding is the ultimate goal of statistics education, paving the way for students to become savvy data analysts.
Linear Regression
Linear regression is a staple in statistical analysis, offering a straightforward way to model the relationship between two variables. It helps us understand how the dependent variable, often denoted as \( y \), changes with the independent variable, \( x \). This method is primarily used when the relationship between these variables can be approximated as a line.

The core formula for a linear regression line is \( y = mx + c \), where \( m \) represents the slope, and \( c \) is the y-intercept. The slope \( m \) indicates how much \( y \) is expected to change for a unit change in \( x \). Calculating \( m \) and \( c \) involves using data points to minimize the difference between estimated values and actual data. The goal is to attain the best fit line, which predicts new data points based on existing data.

Linear regression is particularly useful in educational statistics as it simplifies complex data into a comprehensible model. It illustrates the tangible impacts of changes in one variable on another, providing clarity and understanding of the dataset. When applied, as in our Arkansas city data, linear regression reveals the connection between education status and crime rates, informing strategic community improvements.
Predictive Modeling
Predictive modeling is a powerful tool in data science and statistics, allowing us to forecast future outcomes based on historical data. It uses various statistical techniques, including regression analysis, to predict what might happen under specific conditions. It's widely used in many fields such as finance, marketing, and healthcare.

In the context of our exercise, predictive modeling leverages the regression equation to estimate future data points. Essentially, it answers what's likely to happen if certain trends continue. In our example, predicting the crime rate based on graduation rates is a type of predictive modeling. By modeling these parameters, decision-makers can preemptively address potential issues and make informed policy choices.

The effectiveness of predictive modeling relies on the quality and relevancy of the data used. It's critical to ensure that the dataset is comprehensive and representative of the population it aims to describe. While predictive modeling can provide significant insights, the predictions themselves must always be interpreted within context. Understanding possible anomalies or changes in patterns far beyond the data sample is crucial in making reliable forecasts.

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Most popular questions from this chapter

Is the magnitude of an earthquake related to the depth below the surface at which the quake occurs? Let \(x\) be the magnitude of an earthquake (on the Richter scale), and let \(y\) be the depth (in kilometers) of the quake below the surface at the epicenter. The following is based on information taken from the National Earthquake Information Service of the U.S. Geological Survey. Additional data may be found by visiting the Brase/Brase statistics site at $$ \begin{array}{l|lllllll} \hline x & 2.9 & 4.2 & 3.3 & 4.5 & 2.6 & 3.2 & 3.4 \\ \hline y & 5.0 & 10.0 & 11.2 & 10.0 & 7.9 & 3.9 & 5.5 \\ \hline \end{array} $$ (a) Make a scatter diagram and draw the line you think best fits the data. (b) Would you say the correlation is low, moderate, or strong? positive or negative? (c) Use a calculator to verify that \(\Sigma x=24.1, \Sigma x^{2}=85.75, \Sigma y=53.5\), \(\Sigma y^{2}=458.31\), and \(\Sigma x y=190.18\). Compute \(r .\) As \(x\) increases, does the value of \(r\) imply that \(y\) should tend to increase or decrease? Explain.

In the least squares line \(\hat{y}=5+3 x\), what is the marginal change in \(\hat{y}\) for each unit change in \(x\) ?

Prisons Does prison really deter violent crime? Let \(x\) represent percent change in the rate of violent crime and \(y\) represent percent change in the rate of imprisonment in the general U.S. population. For 7 recent years, the following data have been obtained (Source: The Crime Drop in America, edited by Blumstein and Wallman, Cambridge University Press). $$ \begin{array}{l|rrrrrrr} \hline x & 6.1 & 5.7 & 3.9 & 5.2 & 6.2 & 6.5 & 11.1 \\ \hline y & -1.4 & -4.1 & -7.0 & -4.0 & 3.6 & -0.1 & -4.4 \\ \hline \end{array} $$ Complete parts (a) through (e), given \(\Sigma x=44.7, \Sigma y=-17.4, \Sigma x^{2}=315.85\), \(\Sigma y^{2}=116.1, \Sigma x y=-107.18\), and \(r \approx 0.084 .\) (f) Critical Thinking Considering the values of \(r\) and \(r^{2}\), does it make sense to use the least-squares line for prediction? Explain.

A motion picture industry analyst is studying movies based on epic novels. The following data were obtained for 10 Hollywood movies made in the past five years. Each movie was based on an epic novel. For these data, \(x_{1}=\) first- year box office receipts of the movie, \(x_{2}=\) total production costs of the movie, \(x_{3}=\) total promotional costs of the movie, and \(x_{4}=\) total book sales prior to movie release. All units are in millions of dollars. $$ \begin{array}{rrrr|rrrr} \hline x_{1} & x_{2} & x_{3} & x_{4} & x_{1} & x_{2} & x_{3} & x_{4} \\ \hline 85.1 & 8.5 & 5.1 & 4.7 & 30.3 & 3.5 & 1.2 & 3.5 \\ 106.3 & 12.9 & 5.8 & 8.8 & 79.4 & 9.2 & 3.7 & 9.7 \\ 50.2 & 5.2 & 2.1 & 15.1 & 91.0 & 9.0 & 7.6 & 5.9 \\ 130.6 & 10.7 & 8.4 & 12.2 & 135.4 & 15.1 & 7.7 & 20.8 \\ 54.8 & 3.1 & 2.9 & 10.6 & 89.3 & 10.2 & 4.5 & 7.9 \\ \hline \end{array} $$ (a) Generate summary statistics, including the mean and standard deviation of each variable. Compute the coefficient of variation (see Section \(3.2\) ) for each variable. Relative to its mean, which variable has the largest spread of data values? Why would a variable with a large coefficient of variation be expected to change a lot relative to its average value? Although \(x_{1}\) has the largest standard deviation, it has the smallest coefficient of variation. How does the mean of \(x_{1}\) help explain this? (b) For each pair of variables, generate the sample correlation coefficient \(r\). Compute the corresponding coefficient of determination \(r^{2} .\) Which of the three variables \(x_{2}, x_{3}\), and \(x_{4}\) has the least influence on box office receipts? What percent of the variation in box office receipts can be attributed to the corresponding variation in production costs? (c) Perform a regression analysis with \(x_{1}\) as the response variable. Use \(x_{2}, x_{3}\), and \(x_{4}\) as explanatory variables. Look at the coefficient of multiple determination. What percentage of the variation in \(x_{1}\) can be explained by the corresponding variations in \(x_{2}, x_{3}\), and \(x_{4}\) taken together? (d) Write out the regression equation. Explain how each coefficient can be thought of as a slope. If \(x_{2}\) (production costs) and \(x_{4}\) (book sales) were held fixed but \(x_{3}\) (promotional costs) was increased by \(\$ 1\) million, what would you expect for the corresponding change in \(x_{1}\) (box office receipts)? (e) Test each coefficient in the regression equation to determine if it is zero or not zero. Use level of significance \(5 \%\). Explain why book sales \(x_{4}\) probably are not contributing much information in the regression model to forecast box office receipts \(x_{1}\). (f) Find a \(90 \%\) confidence interval for each coefficient. (g) Suppose a new movie (based on an epic novel) has just been released. Production costs were \(x_{2}=11.4\) million; promotion costs were \(x_{3}=4.7\) million; book sales were \(x_{4}=8.1\) million. Make a prediction for \(x_{1}=\) firstyear box office receipts and find an \(85 \%\) confidence interval for your prediction (if your software supports prediction intervals). (h) Construct a new regression model with \(x_{3}\) as the response variable and \(x_{1}\), \(x_{2}\), and \(x_{4}\) as explanatory variables. Suppose Hollywood is planning a new epic movie with projected box office sales \(x_{1}=100\) million and production costs \(x_{2}=12\) million. The book on which the movie is based had sales of \(x_{4}=9.2\) million. Forecast the dollar amount (in millions) that should be budgeted for promotion costs \(x_{3}\) and find an \(80 \%\) confidence interval for your prediction.

The following data are based on information from the Harvard Business Review (Vol. 72, No. 1). Let \(x\) be the number of different research programs, and let \(y\) be the mean number of patents per program. As in any business, a company can spread itself too thin. For example, too many research programs might lead to a decline in overall research productivity. The following data are for a collection of pharmaceutical companies and their research programs: $$ \begin{array}{l|rrrrrr} \hline x & 10 & 12 & 14 & 16 & 18 & 20 \\ \hline y & 1.8 & 1.7 & 1.5 & 1.4 & 1.0 & 0.7 \\ \hline \end{array} $$ Complete parts (a) through (e), given \(\Sigma x=90, \Sigma y=8.1, \Sigma x^{2}=1420\), \(\Sigma y^{2}=11.83, \Sigma x y=113.8\), and \(r \approx-0.973 .\) (f) Suppose a pharmaceutical company has 15 different research programs. What does the least-squares equation forecast for \(y=\) mean number of patents per program?

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