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Ch. 3 - Describing, Exploring, and Comparing Data
Triola - Elementary Statistics 14th Edition
Triola14th EditionElementary StatisticsISBN: 9780137366446Not the one you use?Change textbook
Chapter 3, Problem 3.CRE.5

Correlation Between Magnitudes and Depths Using the paired magnitude/depth data, construct the graph that is helpful in determining whether there is a correlation between earthquake magnitudes and depths. Based on the result, does there appear to be a correlation?
Table displaying paired data of earthquake magnitudes and depths in kilometers for correlation analysis.
Table displaying paired data of earthquake magnitudes and depths for correlation analysis.
Table displaying paired data of earthquake magnitudes and depths with values 2.44, 8.1, 1.64, and 7.0.

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Step 1: Organize the paired data into two variables: Magnitude (X) and Depth (Y). This will help in visualizing the relationship between the two variables.
Step 2: Create a scatter plot with Magnitude on the x-axis and Depth on the y-axis. Each pair of values (Magnitude, Depth) will be represented as a point on the graph.
Step 3: Observe the pattern of the points on the scatter plot. If the points tend to form a clear upward or downward trend, it suggests a potential correlation. If the points are scattered randomly, it suggests no correlation.
Step 4: Calculate the correlation coefficient (r) using the formula: r = (Σ((X_i - X̄)(Y_i - Ȳ))) / (sqrt(Σ(X_i - X̄)^2) * sqrt(Σ(Y_i - Ȳ)^2)). This will quantify the strength and direction of the relationship between Magnitude and Depth.
Step 5: Interpret the correlation coefficient. If r is close to 1 or -1, there is a strong correlation (positive or negative). If r is close to 0, there is little to no correlation. Use this result to determine whether there appears to be a correlation between earthquake magnitudes and depths.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Correlation

Correlation is a statistical measure that describes the extent to which two variables change together. A positive correlation indicates that as one variable increases, the other tends to increase as well, while a negative correlation suggests that as one variable increases, the other decreases. Understanding correlation is essential for analyzing relationships between earthquake magnitudes and depths, as it helps determine if a pattern exists.
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Scatter Plot

A scatter plot is a graphical representation of two variables, where each point represents an observation in the dataset. In the context of earthquake data, plotting magnitudes against depths allows for visual assessment of any correlation. The pattern of the points can indicate whether there is a linear relationship, clustering, or no apparent relationship between the two variables.
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Magnitude and Depth of Earthquakes

Magnitude measures the energy released during an earthquake, while depth refers to how far below the Earth's surface the earthquake occurs. Analyzing the relationship between these two factors can provide insights into seismic activity and its potential impact. Understanding these concepts is crucial for interpreting the results of the correlation analysis and making informed conclusions about earthquake behavior.
Related Practice
Textbook Question

Sugar Listed below are measured weights (mg) of sugar in Domino packets labelled as containing 3500 mg (or 3.5 g).


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d. Given that the weights are from Domino sugar packets selected from a much larger population, are the weights a sample or a population?

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Textbook Question

Roller Coaster Speed Outlier Identify any outliers among the data listed for Exercise 1.

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Textbook Question

Boxplot Using the same differences from Exercise 1, construct a boxplot and include the values of the 5-number summary.

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Textbook Question

z Scores. In Exercises 5–8, express all z scores with two decimal places.


New York City Commute Time New York City commute times (minutes) are listed in Data Set 31 “Commute Times” in Appendix B. The 1000 times have a mean of 42.6 minutes and a standard deviation of 26.2 minutes. Consider the commute time of 95.0 minutes.


a. What is the difference between the commute time of 95.0 minutes and the mean commute time?

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Textbook Question

z Scores. In Exercises 5–8, express all z scores with two decimal places.


Diastolic Blood Pressure of Females For the diastolic blood pressure measurements of females listed in Data Set 1 “Body Data” in Appendix B, the highest measurement is 98 mm Hg. The 147 diastolic blood pressure measurements of females have a mean of 70.2 mm Hg and a standard deviation of 11.2 mm Hg.


a. What is the difference between the highest diastolic blood pressure and the mean of the diastolic blood pressures for females?

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Textbook Question

Normal Distribution Examine the distribution shown in the histogram from Exercise 6. Does it appear that the sample data are from a population with a normal distribution? Why or why not?

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