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91Ó°ÊÓ

Over the past 30 years in the United States, there has been a strong negative correlation between the number of infant deaths at birth and the number of people over age 65 (a) Is the fact that people are living longer causing a decrease in infant mortalities at birth? (b) What lurking variables might be causing the increase in one or both of the variables? Explain.

Short Answer

Expert verified
(a) No, there's no causal link; correlation doesn't imply causation. (b) Lurking variables could include healthcare improvements, nutrition, and socioeconomic changes.

Step by step solution

01

Understand Correlation vs. Causation

A negative correlation between two variables means that as one variable increases, the other tends to decrease. However, correlation does not imply causation. This means that just because two variables have a correlation, it doesn’t mean one causes the other. In this case, the increase in people living over age 65 might correlate with the decrease in infant mortality, but it does not mean one causes the other to change.
02

Analyzing Question (a)

In question (a), we assess if living longer is causing a decrease in infant deaths. Causation would require a direct link or mechanism showing that older populations affect infant mortality, which seems unlikely. It's more probable that improvements in healthcare or socioeconomic conditions benefit both older adults and infants, reducing mortality rates.
03

Identify Lurking Variables for (b)

Consider variables that independently influence both infant mortality and longevity. These might include healthcare improvements, better nutrition, public health policies, or socioeconomic progress. Such factors can enhance survival chances of infants and increase longevity, explaining the observed correlation without direct causation.

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Key Concepts

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

Negative Correlation
When you hear the term "negative correlation," think about a seesaw: as one side goes up, the other tends to go down. It's the same with correlated variables. For example, if we observe a negative correlation between infant deaths and elderly population growth, it suggests that as fewer infants die, more people seem to live past 65.
However, remember that correlation does not imply causation. Just because these two happenings occur together, it doesn't mean one is directly causing the other. They might be connected, but in reality, they could both be the result of entirely different factors, like improved healthcare or changing social conditions.
This misunderstanding can lead to incorrect conclusions, which is why recognizing the difference between correlation and causation is crucial.
Lurking Variables
Lurking variables are the hidden players in our data puzzle. They are variables that we might not immediately consider but can influence the primary variables we are studying.
Take infant mortality rates and the number of elderly people. Even though we see a change in these rates, there might be unseen factors at play influencing both outcomes. These lurking variables could be improved healthcare systems, better nutrition, or more comprehensive education about health. Each of these can independently affect both the number of infant deaths and the lifespan of older individuals.
Identifying such variables is key to truly understanding relationships in data, preventing us from making misleading causal claims.
Healthcare Improvements
Healthcare improvements have a profound impact on communities. As medical knowledge advances and healthcare access improves, we witness better health outcomes.
Such improvements can lead to a decrease in infant mortality by providing better neonatal care and preventing diseases that can affect newborns. Simultaneously, advancements in medical technology and treatments can extend the lives of the elderly, allowing more people to live past 65.
Thus, when thinking about our correlation puzzle, it's likely that the strides in healthcare over the past 30 years are a critical factor reducing infant deaths while increasing the longevity of older generations.
Socioeconomic Conditions
Socioeconomic conditions encompass factors like income levels, education, employment, and living conditions. These elements play a critical role in determining overall health outcomes within populations.
For instance, as socioeconomic status improves, people often have better access to medical care, healthier food, and a cleaner living environment. This can lead to lower infant mortality rates because better prenatal and postnatal care becomes available. At the same time, individuals may live longer because they benefit from improved diets, healthcare, and living conditions.
In summary, better socioeconomic conditions could be a hidden factor influencing both the reduction of infant deaths and the increase in the elderly population, further explaining the observed negative correlation without implying direct causation.

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Most popular questions from this chapter

Over the past few years, there has been a strong positive correlation between the annual consumption of diet soda drinks and the number of traffic accidents. (a) Do you think increasing consumption of diet soda drinks causes traffic accidents? Explain. (b) What lurking variables might be causing the increase in one or both of the variables? Explain.

Please do the following. (a) Draw a scatter diagram displaying the data. (b) Verify the given sums \(\Sigma x, \Sigma y, \Sigma x^{2}, \Sigma y^{2},\) and \(\Sigma x y\) and the value of the sample correlation coefficient \(r\) (c) Find \(\bar{x}, \bar{y}, a,\) and \(b .\) Then find the equation of the least- squares line \(\hat{y}=a+b x\) (d) Graph the least-squares line on your scatter diagram. Be sure to use the point \((\bar{x}, \bar{y})\) as one of the points on the line. (e) Interpretation Find the value of the coefficient of determination \(r^{2} .\) What percentage of the variation in \(y\) can be explained by the corresponding variation in \(x\) and the least-squares line? What percentage is unexplained? Answers may vary slightly due to rounding. Let \(x\) be the age of a licensed driver in years. Let \(y\) be the percentage of all fatal accidents (for a given age) due to failure to yield the right-of- way. For example, the first data pair states that \(5 \%\) of all fatal accidents of 37 -year-olds are due to failure to yield the right-of-way. The Wall Street Journal article referenced in Problem 11 reported the following data: Complete parts (a) through (e), given \(\Sigma x=372, \Sigma y=112, \Sigma x^{2}=24,814\) \(\Sigma y^{2}=3194, \Sigma x y=8254,\) and \(r \approx-0.943\) (f) Predict the percentage of all fatal accidents due to failing to yield the right-of-way for 70-year-olds.

In baseball, is there a linear correlation between batting average and home run percentage? Let \(x\) represent the batting average of a professional baseball player, and let \(y\) represent the player's home run percentage (number of home runs per 100 times at bat). A random sample of \(n=7\) professional baseball players gave the following information (Reference: The Baseball Encyclopedia, Macmillan Publishing Company). (a) Make a scatter diagram and draw the line you think best fits the data. (b) Would you say the correlation is low, moderate, or high? positive or negative? (c) Use a calculator to verify that \(\Sigma x=1.957, \Sigma x^{2} \approx 0.553, \Sigma y=30.1\) \(\Sigma y^{2}=150.15,\) and \(\Sigma x y \approx 8.753 .\) Compute \(r .\) As \(x\) increases, does the value of \(r\) imply that \(y\) should tend to increase or decrease? Explain.

If two variables have a negative linear correlation, is the slope of the least-squares line positive or negative?

Please do the following. (a) Draw a scatter diagram displaying the data. (b) Verify the given sums \(\Sigma x, \Sigma y, \Sigma x^{2}, \Sigma y^{2},\) and \(\Sigma x y\) and the value of the sample correlation coefficient \(r\) (c) Find \(\bar{x}, \bar{y}, a,\) and \(b .\) Then find the equation of the least- squares line \(\hat{y}=a+b x\) (d) Graph the least-squares line on your scatter diagram. Be sure to use the point \((\bar{x}, \bar{y})\) as one of the points on the line. (e) Interpretation Find the value of the coefficient of determination \(r^{2} .\) What percentage of the variation in \(y\) can be explained by the corresponding variation in \(x\) and the least-squares line? What percentage is unexplained? Answers may vary slightly due to rounding. Jobs An economist is studying the job market in Denver-area neighborhoods. Let \(x\) represent the total number of jobs in a given neighborhood, and let \(y\) represent the number of entry-level jobs in the same neighborhood. A sample of six Denver neighborhoods gave the following information (units in hundreds of jobs).Complete parts (a) through (e), given \(2 x=202,2 y=28, \Sigma x^{2}=7754\) \(\Sigma y^{2}=164, \Sigma x y=1096,\) and \(r \approx 0.860\) (f) For a neighborhood with \(x=40\) jobs, how many are predicted to be entry- level jobs?

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