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More predictions Hurricane Katrina's hurricane force winds extended 120 miles from its center. Katrina was a big storm, and that affects how we think about the prediction errors. Suppose we add 120 miles to each error to get an idea of how far from the predicted track we might still find damaging winds. Explain what would happen to the correlation between Prediction Error and Year, and why.

Short Answer

Expert verified
The correlation between Prediction Error and Year would not change, even if 120 miles are added to each Prediction Error. This is because the correlation between two variables is not affected by adding or subtracting a constant.

Step by step solution

01

Understand Correlation

Correlation is a statistical measure that indicates the extent to which two or more variables fluctuate together. A positive correlation indicates the extent to which those variables increase or decrease in parallel; a negative correlation indicates the extent to which one variable increases as the other decreases.
02

Understand the problem

In this problem, we are assuming that we add 120 miles to each error and are asked about the effect on the correlation between Prediction Error and Year.
03

Effect of adding a constant on correlation

Adding or subtracting a constant from every value of a single variable will not affect the correlation between that variable and another variable. The spread and relationship between the two sets of data remains the same, so the correlation does not change. By adding 120 miles to each error, the errors are simply translated upwards, but their relationship with the years remains the same. So, the correlation between Prediction Error and Year won't change.
04

Conclusion

Even though the absolute values of the Prediction Errors would increase by 120 miles, their correlation with the Year won't change. This is because correlation only measures how Prediction Error and Year move together, not their specific values.

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Key Concepts

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

Prediction Error
Prediction error refers to the difference between the predicted value and the actual outcome. In the context of hurricanes, this could mean the difference between the predicted path of the storm and where the storm actually goes. Understanding prediction errors is crucial because it helps us assess how reliable our forecasts are.
Large prediction errors can indicate a need for improved modeling techniques. Small errors, on the other hand, suggest that the prediction models are relatively accurate. When we talk about adding 120 miles to each prediction error, we're essentially considering potential deviations to understand better where the damaging winds might impact. This does not alter the inherent relationship between prediction error and other factors like the year the storm occurs in, but rather just shifts our perspective on the variability of the error.
Statistical Measure
In statistics, a statistical measure is a value that represents some property of a data set, providing insight into its characteristics. Correlation is a well-known statistical measure, often expressed by the correlation coefficient.
This coefficient ranges from -1 to 1. A value closer to 1 indicates a strong positive relationship, meaning as one variable increases, so does the other. Conversely, a correlation near -1 signifies a strong negative relationship, where one variable increases as the other decreases.
When we look at correlation in terms of prediction error and another variable like the year, we use this measure to understand if prediction errors are increasing, decreasing, or remaining constant over time. This insight is crucial for evaluating the effectiveness of forecasting methods over different periods.
Variable Fluctuation
Variable fluctuation analyzes how the data values within a dataset change. When assessing variables, such as prediction errors across years, we look for patterns of rise or fall. This helps inform how unpredictable factors like hurricanes are managed over different time spans.
Variable fluctuation can show trends, such as whether hurricanes are becoming harder to predict over time or if they follow a cyclical pattern. This knowledge can then lead to more strategic planning and better allocation of resources to mitigate the impact of such natural phenomena.
Understanding fluctuations also plays a role in improving prediction models, as it enables forecasters to adapt their methods to the evolving nature of the data and environmental conditions.
Effect of Constants on Correlation
When a constant is added to a dataset, like adding 120 miles to each prediction error in this exercise, the correlation between that dataset and another variable, such as the year, does not change. This is because correlation measures how two variables move together, not their specific sizes.
Adding a constant translates the data without affecting the overall shape or direction of its relationship with another variable. Thus, the correlation remains unchanged.
This property is vital in statistics as it ensures that the underlying relationships between variables are preserved, even if transformations are applied to the data. It emphasizes that correlation reflects the pattern of co-movement, not shifts in magnitude due to constants.

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Most popular questions from this chapter

Smartphones and life expectancy A survey of the world's nations in 2014 shows a strong positive correlation between percentage of the country using smartphones and life expectancy in years at birth. a. Does this mean that smartphones are good for your health? b. What might explain the strong correlation?

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The errors in predicting hurricane tracks (examined in this chapter) were given in nautical miles. A statutory mile is 0.86898 nautical mile. Most people living on the Gulf Coast of the United States would prefer to know the prediction errors in statutory miles rather than nautical miles. Explain why converting the errors to statutory miles would not change the correlation between Prediction Error and Year.

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