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Chapter 4: Q. 57 (page 264)

Cocoa and blood flow A study of blood flow involved 27healthy people aged 18to 72. Each subject consumed a cocoa beverage containing 900milligrams of flavonols daily for 5days. Using a finger cuff, blood flow was measured on the first and fifth days of the study. After 5 days, researchers measured what they called “significant improvement” in blood flow and the function of the cells that line the blood vessels. What flaw in the design of this experiment makes it impossible to say if the cocoa really caused the improved blood flow? Explain your answer.

Short Answer

Expert verified

Irregularity in checkups makes it impossible to say if the cocoa really caused the improved blood flow.

Step by step solution

01

Given information

We are given that a study was conducted to check if the cocoa really caused the improved blood flow.

02

Simplify

Well, there is a flow in this study. Researcher's measured what they called “significant improvement” in blood flow and the function of the cells that line the blood vessels. as Flavanols, which are nutrients found in cocoa, are the active ingredient.
On cells, flavonols are thought to operate as antioxidants and anti-inflammatories.
But the flow is check up is done on the first and fifth days of the study , there can be so many circumstances that can have happened between five days. so it makes it impossible to say if the cocoa really caused the improved blood flow

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Most popular questions from this chapter

One of the better studies of the effect of regular attendance

at religious services gathered data from a random sample of 3617 adults. The researchers then measured lots of variables, not just the explanatory variable (religious activities) and the response variable (length of life). A news article said: “Churchgoers were more likely to be nonsmokers, physically active, and at their right weight. But even after health behaviors were taken into account, those not attending religious services regularly still were significantly more likely to have died.” What conclusion can we draw from this study? Explain your reasoning.

Two essential features of all statistically designed experiments are

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e. using enough subjects; always having a control group.

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c. The difference is due to undercoverage bias. The survey included only adults and did

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SRS of students? At a party, there are 30 students over age 21 and 20students underage21. You choose at random 3 of those over 21 and separately choose at random 2 of those under 21 to interview about their attitudes toward alcohol. You have given every student at the party the same chance to be interviewed. Is your sample an SRS? Explain your answer.
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