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What do the y-coordinates on the least-squares regression line represent?

Short Answer

Expert verified
The y-coordinates on the least-squares regression line are the predicted values of the dependent variable for given values of the independent variable.

Step by step solution

01

Definition of Least-Squares Regression Line

The least-squares regression line is a straight line that best fits the data points on a scatter plot. It minimizes the sum of the squares of the vertical distances of the points from the line.
02

Determine the Purpose of the Regression Line

The regression line is used to describe how one variable (dependent variable) changes with respect to another variable (independent variable). It's used for prediction purposes.
03

Interpret the Y-Coordinates

The y-coordinates on the least-squares regression line represent the predicted values of the dependent variable given specific values of the independent variable. These values are the best approximation of the actual data points, according to the linear relationship established by the regression.

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Key Concepts

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

Dependent Variable
In the context of a least-squares regression line, the dependent variable represents the outcome we are trying to predict or explain. This variable is plotted on the y-axis of a scatter plot. For instance, if we're looking at the effect of study hours on test scores, the test scores would be our dependent variable.
The y-coordinates on the regression line show the predicted values of this dependent variable for different given values of the independent variable. So, whenever we input a value for the independent variable into our regression equation, the output will be the predicted value of the dependent variable.
Independent Variable
The independent variable is the variable we use to make predictions or explain the dependent variable. This is plotted on the x-axis of a scatter plot. For example, in examining the relationship between study hours and test scores, the number of study hours would be our independent variable.
The regression line tells us how changes in the independent variable affect the dependent variable. When we use the least-squares regression line, we are finding the best-fit line that minimizes the distances between the actual data points and the predicted values (y-coordinates) on the regression line.
It's important to understand that the independent variable is the one you have control over or are exploring to see its impact on the dependent variable.
Scatter Plot
A scatter plot is a type of graph that shows the relationship between two variables using dots to represent data points. Each point on the scatter plot corresponds to one observation with coordinates \(x_i, y_i\), where \(x_i\) is a value of the independent variable and \(y_i\) is the corresponding value of the dependent variable.
By visually analyzing the scatter plot, we can identify patterns, trends, and potential correlations between the variables. When we add a least-squares regression line to the scatter plot, it helps us understand the direction and strength of the relationship.
If the points are closely clustered around the line, it indicates a strong relationship. Conversely, if the points are widely scattered, the relationship might be weaker.
Predictive Modeling
Predictive modeling involves using statistical techniques to forecast future data points based on current and historical data. One common technique is using a least-squares regression line, which helps us predict the dependent variable based on the given values of the independent variable.
In predictive modeling, the goal is to create a model that can produce accurate and reliable predictions. The least-squares regression line is particularly useful because it minimizes the prediction errors by reducing the sum of the squares of these errors.
This method is widely used in various fields such as economics, engineering, biology, and social sciences to make informed decisions and predictions about future trends and outcomes.

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Most popular questions from this chapter

You obtain the multiple regression equation \(\hat{y}=5+3 x_{1}-4 x_{2}\) from a set of sample data. (a) Interpret the slope coefficients for \(x_{1}\) and \(x_{2}\). (b) Determine the regression equation with \(x_{1}=10\). Graph the regression equation with \(x_{1}=10\). (c) Determine the regression equation with \(x_{1}=15 .\) Graph the regression equation with \(x_{1}=15\) (d) Determine the regression equation with \(x_{1}=20 .\) Graph the regression equation with \(x_{1}=20 .\) (e) What is the effect of changing the value \(x_{1}\) on the graph of the regression equation?

Researchers developed a model to explain the age gap between husbands and wives at first marriage. The model is below: $$ \hat{y}=0.0321 x_{1}+0.9848 x_{2}+0.5391 x_{3}-0.000145 x_{4}^{2}+3.8483 $$ where y: Age gap at first marriage (male - female) \(x_{1}:\) Percent of children aged 10 to 14 involved in child labor \(x_{2}:\) Indicator variable where 1 is an African country, 0 otherwise \(x_{3}:\) Percent of the population that is Muslim \(x_{4}:\) Percent of the population that is literate Source: Xu Zhang and Solomon W. Polachek, State University of New York at Binghamton "The Husband- Wife Age Gap at First Marriage: A Cross-Country Analysis" (a) Use the model to predict the age gap at first marriage for an African country where the percent of children aged 10 to 14 who are involved in child labor is \(12,\) the percent of the population that is Muslim is \(30,\) and the percent of the population that is literate is \(75 .\) (b) What would be the mean difference in age gap between an African country and a non-African country? (c) Interpret the coefficient of "percent of children aged 10 to 14 involved in child labor." (d) The coefficient of determination for this model is 0.593 . Interpret this result. (e) The \(P\) -value for the test \(H_{1}: \beta_{1} \neq 0\) versus \(H_{1}: \beta_{1} \neq 0\) is \(0.008 .\) What would you conclude about this test?

For the data set. $$ \begin{array}{cllc} x_{1} & x_{2} & x_{3} & y \\ \hline 0.8 & 2.8 & 2.5 & 11.0 \\ \hline 3.9 & 2.6 & 5.7 & 10.8 \\ \hline 1.8 & 2.4 & 7.8 & 10.6 \\\ \hline 5.1 & 2.3 & 7.1 & 10.3 \\ \hline 4.9 & 2.5 & 5.9 & 10.3 \\ \hline 8.4 & 2.1 & 8.6 & 10.3 \\ \hline 12.9 & 2.3 & 9.2 & 10.0 \\ \hline 6.0 & 2.0 & 1.2 & 9.4 \\ \hline 14.6 & 2.2 & 3.7 & 8.7 \\ \hline 93 & 11 & 55 & 87 \end{array} $$ (a) Construct a correlation matrix between \(x_{1}, x_{2}, x_{3},\) and \(y .\) Is there any evidence that multicollinearity exists? Why? (b) Determine the multiple regression line with \(x_{1}, x_{2},\) and \(x_{3}\) as the explanatory variables. (c) Assuming that the requirements of the model are satisfied, test \(H_{0}: \beta_{1}=\beta_{2}=\beta_{3}=0\) versus \(H_{1}:\) at least one of the \(\beta_{i}\) is different from zero at the \(\alpha=0.05\) level of significance. (d) Assuming that the requirements of the model are satisfied, test \(H_{0}: \beta_{i}=0\) versus \(H_{1}: \beta_{i} \neq 0\) for \(i=1,2,3\) at the \(\alpha=0.05\) level of significance.

4\. Suppose you want to develop a model that predicts the gas mileage of a car. The explanatory variables you are going to utilize are \(x_{1}:\) city or highway driving \(x_{2}:\) weight of the car \(x_{3}:\) tire pressure (a) Write a model that utilizes all three explanatory variables in an additive model with linear terms and define any indicator variables. (b) Suppose you suspect there is interaction between weight and tire pressure. Write a model that incorporates this interaction term into the model from part (a).

An economist was interested in modeling the relation among annual income, level of education, and work experience. The level of education is the number of years of education beyond eighth grade, so 1 represents completing I year of high school, 8 means completing 4 years of college, and so on. Work experience is the number of years employed in the current profession. From a random sample of 12 individuals, he obtained the following data: $$ \begin{array}{ccc} \begin{array}{l} \text { Work Experience } \\ \text { (years) } \end{array} & \begin{array}{l} \text { Level of } \\ \text { Education } \end{array} & \begin{array}{l} \text { Annual Income } \\ \text { (\$ thousands) } \end{array} \\ \hline 21 & 6 & 34.7 \\ \hline 14 & 3 & 17.9 \\ \hline 4 & 8 & 22.7 \\\ \hline 16 & 8 & 63.1 \\ \hline 12 & 4 & 33.0 \\ \hline 20 & 4 & 41.4 \\\ \hline 25 & 1 & 20.7 \\ \hline 8 & 3 & 14.6 \\ \hline 24 & 12 & 97.3 \\\ \hline 28 & 9 & 72.1 \\ \hline 4 & 11 & 49.1 \\ \hline 15 & 4 & 52.0 \\\ \hline \end{array} $$ (a) Construct a correlation matrix between work experience, level of education, and annual income. Is there any reason to be concerned with multicollinearity based on the correlation matrix? (b) Find the least-squares regression equation \(\hat{y}=b_{0}+\) \(b_{1} x_{1}+b_{2} x_{2},\) where \(x_{1}\) is work experience, \(x_{2}\) is level of education, and \(y\) is the response variable, annual income. (c) Draw residual plots and a boxplot of the residuals to assess the adequacy of the model. (d) Interpret the regression coefficients for the least-squares regression equation. (e) Determine and interpret \(R^{2}\) and the adjusted \(R^{2}\) (f) Test \(H_{0}: \beta_{1}=\beta_{2}=0\) versus \(H_{1} ;\) at least one of the \(\beta_{i} \neq 0\) at the \(\alpha=0.05\) level of significance. (g) Test the hypotheses \(H_{0}: \beta_{1}=0\) versus \(H_{1}: \beta_{1} \neq 0\) and \(H_{0}: \beta_{2}=0\) versus \(H_{1}: \beta_{2} \neq 0\) at the \(\alpha=0.05\) level of significance. (h) Predict the mean income of all individuals whose experience is 12 years and level of education is 4 (i) Predict the income of a single individual whose experience is 12 years and level of education is 4 (j) Construct \(95 \%\) confidence and prediction intervals for income when experience is 12 years and level of education is 4

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