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The article "Behavioural Effects of Mobile Telephone Use During Simulated Driving" (Ergonomics, 1995: 2536-2562) reported that for a sample of 20 experimental subjects, the sample correlation coefficient for \(x=\) age and \(y=\) time since the subject had acquired a driving license (yr) was \(.97\). Why do you think the value of \(r\) is so close to 1 ? (The article's authors gave an explanation.)

Short Answer

Expert verified
The high correlation is due to age and years since obtaining a license naturally increasing together over time.

Step by step solution

01

Understand the parameters

We are given the correlation coefficient \(r = 0.97\) for variables \(x\) and \(y\). Here, \(x\) is the age of the subjects, and \(y\) is the time since the subjects obtained their driving license.
02

Interpret the correlation coefficient

The correlation coefficient \(r = 0.97\) indicates a very strong positive linear relationship between age and time since acquiring a driving license. This means as age increases, the time since the subject obtained their driving license also increases almost linearly.
03

Consider natural associations

Typically, people obtain their driving licenses around the same age (usually late teens or early twenties). Therefore, there will be a strong association over the years as both age and years since obtaining their driving license increase simultaneously.
04

Explain the high correlation

The nearly perfect correlation (\(r = 0.97\)) is likely because increments in age naturally correspond to increments in the time since they got their driving license. This is expected since both measures increase simultaneously as years pass.

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Key Concepts

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

Linear Relationship
A linear relationship is one where two variables increase or decrease together at a consistent rate. In the context of the given exercise, we are examining a linear relationship between age and the time since obtaining a driving license. When we say there is a linear relationship here, it implies that for every increase in age, there is a predictable and steady increase in the time since a person got their license. The slope of this relationship in a graph would be almost a straight line, showcasing consistency in how these two variables relate.

In mathematical terms, the correlation coefficient \( r = 0.97 \) tells us that this line is very close to being perfectly straight, which would be 1. This near-perfect correlation suggests that as people get older, the number of years since they were first able to drive increases almost uniformly. The closer the value of \( r \) is to 1, the more confidently we can assert that there is a strong and direct linear relationship between the two data sets. This kind of consistency and predictability can be helpful in various statistical and real-world applications.
Statistical Analysis
Statistical analysis involves examining data to uncover patterns, trends, or relationships. In our exercise, statistical analysis focuses on determining how two variables, age, and time since acquiring a driving license, interact with one another. Through calculations, we find the correlation coefficient, which measures the strength and direction of a linear relationship between two variables.

Calculating a correlation coefficient like \( r \) is a common statistical approach to assess relationships. When \( r \) is close to 1, we conclude a very strong positive linear relationship. This means that not only do the variables move together, but they do so at an expected and consistent rate. Such analysis can help infer the behavior of the dataset and make predictions. For instance, if our correlation shows such a high value, it's a clue that when we know one variable, we have a strong prediction for the other.
  • Identify the variables in your analysis.
  • Calculate the correlation coefficient.
  • Analyze the meaning of \( r \) concerning your data.
  • Use this analysis to understand potential implications.
Understanding these concepts helps us appreciate how statistical tools can make sense of real-world patterns and phenomena.
Data Interpretation
Data interpretation is a crucial step that follows statistical analysis, allowing us to unpack what numerical findings mean in the real world. Our exercise showcases the intersection of understanding data through the correlation coefficient and what that means practically. When we interpret the data with an \( r = 0.97 \), we're turning numbers into narratives.

The high correlation between age and years since obtaining a driver's license tells a story of predictable growth and change. Typically, teens in most countries receive a driving license at a similar age, creating a synchronized rise in both age and license-holding duration. This is why our correlation is so strong; it's a reflection of societal practices.
  • Contextualize the numbers - link the data to real-world scenarios.
  • Understand the variables and their implications.
  • Translate numerical relationships into practical insights.
  • Consider any external factors that might influence the data.
Proper data interpretation gives depth to numbers and transforms them from simple statistics into stories with practical implications, helping us make informed decisions and predictions.

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