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If a slope is 1.50 when \(x=\) income in thousands of dollars, then what is the slope when \(x=\) income in dollars? (Hint: A \(\$ 1\) change has only \(1 / 1000\) of the impact of a \(\$ 1000\) change?)

Short Answer

Expert verified
The slope when income is measured in dollars is 0.0015.

Step by step solution

01

Understanding the Problem

The problem gives a slope of 1.50 when the x-variable (income) is measured in thousands of dollars. The task is to find the slope when x is measured in dollars.
02

Converting the Scale of X

We need to convert the scale from thousands of dollars to a single dollar. In other words, each unit increase in x by 1 thousand dollars changes to an increase in 1 dollar. To convert, note that 1 thousand dollars (1 change of +1 in the x-variable under the original condition) is equivalent to an increase of 1000 individual dollar units.
03

Adjusting the Slope

Originally, an increase of 1 (representing $1000) in the x-variable results in a slope of 1.50.When changing to dollars as units, a unit increment in the x-variable (1 dollar) is one one-thousandth of the original scale step (1000 dollars). Therefore, multiply the original slope by \( \frac{1}{1000} \) to adjust for this scaling.
04

Calculating the New Slope

Multiply the original slope by \( \frac{1}{1000} \):\[ 1.50 \times \frac{1}{1000} = 0.0015 \]Thus, the slope when income is measured in dollars is 0.0015.

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Key Concepts

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

Change of Scale
When dealing with data, one crucial aspect is understanding how changes in the scale can affect the interpretation of results. In this context, we are examining how a change in the unit of measurement from thousands of dollars to individual dollars impacts the slope of a line in a linear model.

A scale change essentially involves multiplying or dividing the entire data set by a constant. In our example, when the income is measured in thousands of dollars, we observe how the slope represents the change in the dependent variable (often considered the outcome or response variable) for every 1000 dollars change in the independent variable. If we switch the measurement to individual dollars, each unit change is now 1/1000 of the original step.

This requires adjusting the slope proportionally by multiplying it by 1/1000, as the impact of each dollar is smaller. Change of scale is a frequent consideration when dealing with data to ensure accurate interpretations, such as when data is collected in different units.
Unit Conversion
Unit conversion is essential in mathematics and statistics for accurately comparing and interpreting different data sets. In the given problem, we are converting between two units: thousands of dollars and dollars.

The procedure involves understanding the relationship between the units and using conversion factors to adjust our values appropriately. The basic conversion here is recognizing that 1 thousand dollars equals 1000 dollars.

To properly adjust calculations like slopes, we apply this conversion factor. For the slope, originally defined per thousand dollars, converting to a per-dollar basis requires calculating the translation of impact:
  • Original slope per thousand dollars is 1.50.
  • New slope per dollar is 1.50 multiplied by 1/1000, resulting in 0.0015.

Understanding how to convert units ensures that the analysis remains meaningful across different scales, which is crucial in decision-making and prediction models.
Linear Regression
Linear regression is a foundational statistical method that models the relationship between an independent variable and a dependent variable as a linear relationship. The equation of a straight line, often written as \( y = mx + b \), describes this relationship. In this equation, \(m\) is the slope, and it shows how much \(y\), our dependent variable, changes with a one unit increase in \(x\), the independent variable.

The problem you're working on involves adjusting this slope due to a change in units of the independent variable. Linear regression provides a valuable tool for prediction, but it also relies on understanding how factors such as measurement scale can influence the results.

Any time the units of \(x\) change, as seen here from thousands of dollars to dollars, there must be corresponding adjustments to the slope. These adjustments ensure that the regression line continues to reflect the true relationship between the variables, allowing for accurate data analysis and prediction. Understanding the intricacies of linear regression, including unit adjustments, is crucial for effective analysis in fields like economics, science, and engineering.

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Most popular questions from this chapter

A clinical trial admits subjects suffering from high cholesterol, who are then randomly assigned to take a drug or a placebo for a 12 -week study. For the population, without taking any drug, the correlation between the cholesterol readings at times 12 weeks apart is 0.70 . The mean cholesterol reading at any given time is 200 , with the same standard deviation at each time. Consider all the subjects with a cholesterol level of 300 at the start of the study, who take placebo. a. What would you predict for their mean cholesterol level at the end of the study? b. Does this suggest that placebo is effective for treating high cholesterol? Explain.

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Last year you looked at all the financial firms that had stock growth funds. You picked the growth fund that had the best performance last year (ranking at the 99 th percentile on performance) and invested all your money in it this year. This year, with their new investments, they ranked only at the 65 th percentile on performance. Your friend suggests that their stock picker became complacent or was burned out. Can you give another explanation?

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