/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 95 Numerous studies have shown that... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

Numerous studies have shown that a high fat diet can have a negative effect on a child's health. A new study \(^{22}\) suggests that a high fat diet early in life might also have a significant effect on memory and spatial ability. In the double-blind study, young rats were randomly assigned to either a high-fat diet group or to a control group. After 12 weeks on the diets, the rats were given tests of their spatial memory. The article states that "spatial memory was significantly impaired" for the high-fat diet rats, and also tells us that "there were no significant differences in amount of time exploring objects" between the two groups. The p-values for the two tests are 0.0001 and 0.7 . (a) Which p-value goes with the test of spatial memory? Which p-value goes with the test of time exploring objects? (b) The title of the article describing the study states "A high-fat diet causes impairment" in spatial memory. Is the wording in the title justified (for rats)? Why or why not?

Short Answer

Expert verified
(a) The p-value for the test of spatial memory is 0.0001 and the p-value for the test of time exploring objects is 0.7. (b) Yes, the wording in the title is justified since there is a statistically significant impairment of spatial memory in rats caused by a high-fat diet.

Step by step solution

01

Identification of P-values

The p-value is a number between 0 and 1 that is used in hypothesis testing to indicate statistical significance. The smaller the p-value, the stronger the evidence is to reject the null hypothesis and accept the alternative hypothesis. In this exercise, two p-values are given: 0.0001 and 0.7. The phrase 'spatial memory was significantly impaired' in the article is a suggestion of strong evidence, i.e., a small p-value. Therefore, the p-value of 0.0001 corresponds to the test of spatial memory. Conversely, the statement 'there were no significant differences in amount of time exploring objects' implies weak or insufficient evidence to reject the null hypothesis. Therefore, the p-value of 0.7 corresponds to the test of time spent exploring objects.
02

Analysis of the Article's Title

The title of the article claims that 'A high-fat diet causes impairment' in spatial memory. From the results of the study, it was found that there is statistical significance (p=0.0001) between the high-fat diet and spatial memory impairment in rats. From a statistical standpoint, it means that there is strong evidence to reject the null hypothesis and accept the alternate hypothesis, which is the high-fat diet has a significant effect on the spatial memory of the rats. Hence, based only on these statistical results, the wording in the title is justified.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

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

Understanding P-Value in Hypothesis Testing
In the realm of statistics, the p-value is a pivotal concept used to measure the strength of evidence against the null hypothesis in hypothesis testing. Imagine a scientist proclaiming they've made a discovery - the p-value helps determine if the evidence is solid enough to back up such a claim. It's essentially a gauge for skepticism, where a low p-value, typically less than 0.05, implies that what was observed is highly unlikely under the assumption that the null hypothesis is true.

Take our rats as subjects for instance. The study noted a p-value of 0.0001 for the spatial memory test. This is so low it virtually erases doubt, strongly indicating that the high-fat diet indeed impairs spatial memory. Contrastingly, a p-value of 0.7 for the object exploration test is high, suggesting that there's no substantial difference between groups in this behavior.

It's crucial to understand that a p-value doesn't measure the magnitude of an effect or outcome, but rather how surprising the results are given the null hypothesis. In education, explaining p-value through clear examples, like the study above, helps students to firmly grasp what it means for a result to be ‘statistically significant’.
Hypothesis Testing: Making Decisions with Data
Hypothesis testing is a formal method used to draw conclusions from data subject to random variation. It’s a foundational stone in statistical analysis. At its heart, it involves setting up two opposing hypotheses: the null hypothesis (ull_hypothesis) which suggests no effect or no difference, and the alternative hypothesis (ull_hypothesis') which posits the existence of an effect or a difference.

In our rat diet experiment, the study is seeking to test the claim that a high-fat diet impacts spatial memory. Here, the null hypothesis would be that the diet has no effect, while the alternative hypothesis would be that it does affect spatial memory. Given the p-value is 0.0001, which is far less than the common alpha level of 0.05, the decision would be to reject the null hypothesis in favor of the alternative.

Teaching students about hypothesis testing involves not just the calculation of numbers but understanding the concept of evidence against the 'status quo' or null hypothesis. Ensuring that they understand the context and assumptions behind each hypothesis is essential for a comprehensive understanding of this statistical technique.
Spatial Memory in Research and Real Life
Spatial memory is an essential cognitive function, allowing organisms to navigate their environment by recalling the location of objects and landmarks. In the context of scientific studies, researchers often assess spatial memory to investigate how different variables may impact cognitive abilities.

In the case of the young rats on a high-fat diet, their impaired spatial memory compared to the control group suggests potential cognitive consequences of dietary choices. While this study pertains to rats, the implications extend to broader concerns about children's diets and development - a crucial point that should resonate with students.

Illustrating the concept of spatial memory with tangible examples, such as animals navigating mazes or even humans remembering where they parked their car, helps students relate the term to their own experiences. This real-world connection not only makes the concept more understandable but can also spark interest in how diet and lifestyle can affect cognitive functions like spatial memory.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Influencing Voters Exercise 4.39 on page 272 describes a possible study to see if there is evidence that a recorded phone call is more effective than a mailed flyer in getting voters to support a certain candidate. The study assumes a significance level of \(\alpha=0.05\) (a) What is the conclusion in the context of thisstudy if the p-value for the test is \(0.027 ?\) (b) In the conclusion in part (a), which type of error are we possibly making: Type I or Type II? Describe what that type of error means in this situation. (c) What is the conclusion if the p-value for the test is \(0.18 ?\)

Euchre One of the authors and some statistician friends have an ongoing series of Euchre games that will stop when one of the two teams is deemed to be statistically significantly better than the other team. Euchre is a card game and each game results in a win for one team and a loss for the other. Only two teams are competing in this series, which we'll call team A and team B. (a) Define the parameter(s) of interest. (b) What are the null and alternative hypotheses if the goal is to determine if either team is statistically significantly better than the other at winning Euchre? (c) What sample statistic(s) would they need to measure as the games go on? (d) Could the winner be determined after one or two games? Why or why not? (e) Which significance level, \(5 \%\) or \(1 \%,\) will make the game last longer?

Figure 4.25 shows a scatterplot of the acidity (pH) for a sample of \(n=53\) Florida lakes vs the average mercury level (ppm) found in fish taken from each lake. The full dataset is introduced in Data 2.4 on page 71 and is available in FloridaLakes. There appears to be a negative trend in the scatterplot, and we wish to test whether there is significant evidence of a negative association between \(\mathrm{pH}\) and mercury levels. (a) What are the null and alternative hypotheses? (b) For these data, a statistical software package produces the following output: $$ r=-0.575 \quad p \text { -value }=0.000017 $$ Use the p-value to give the conclusion of the test. Include an assessment of the strength of the evidence and state your result in terms of rejecting or failing to reject \(H_{0}\) and in terms of \(\mathrm{pH}\) and mercury. (c) Is this convincing evidence that low \(\mathrm{pH}\) causes the average mercury level in fish to increase? Why or why not?

It is well established that exercise is beneficial for our bodies. Recent studies appear to indicate that exercise can also do wonders for our brains, or, at least, the brains of mice. In a randomized experiment, one group of mice was given access to a running wheel while a second group of mice was kept sedentary. According to an article describing the study, "The brains of mice and rats that were allowed to run on wheels pulsed with vigorous, newly born neurons, and those animals then breezed through mazes and other tests of rodent IQ"9 compared to the sedentary mice. Studies are examining the reasons for these beneficial effects of exercise on rodent (and perhaps human) intelligence. High levels of BMP (bonemorphogenetic protein) in the brain seem to make stem cells less active, which makes the brain slower and less nimble. Exercise seems to reduce the level of BMP in the brain. Additionally, exercise increases a brain protein called noggin, which improves the brain's ability. Indeed, large doses of noggin turned mice into "little mouse geniuses," according to Dr. Kessler, one of the lead authors of the study. While research is ongoing in determining how strong the effects are, all evidence points to the fact that exercise is good for the brain. Several tests involving these studies are described. In each case, define the relevant parameters and state the null and alternative hypotheses. (a) Testing to see if there is evidence that mice allowed to exercise have lower levels of BMP in the brain on average than sedentary mice. (b) Testing to see if there is evidence that mice allowed to exercise have higher levels of noggin in the brain on average than sedentary mice. (c) Testing to see if there is evidence of a negative correlation between the level of BMP and the level of noggin in the brains of mice.

Mating Choice and Offspring Fitness Does the ability to choose a mate improve offspring fitness in fruit flies? Researchers have studied this by taking female fruit flies and randomly dividing them into two groups; one group is put into a cage with a large number of males and able to freely choose who to mate with, while flies in the other group are each put into individual vials, each with only one male, giving no choice in who to mate with. Females are then put into egg laying chambers, and a certain number of larvae collected. Do the larvae from the mate choice group exhibit higher survival rates? A study \(^{44}\) published in Nature found that mate choice does increase offspring fitness in fruit flies (with p-value \(<0.02\) ), yet this result went against conventional wisdom in genetics and was quite controversial. Researchers attempted to replicate this result with a series of related experiments, \({ }^{45}\) with data provided in MateChoice. (a) In the first replication experiment, using the same species of fruit fly as the original Nature study, 6067 of the 10000 larvae from the mate choice group survived and 5976 of the 10000 larvae from the no mate choice group survived. Calculate the p-value. (b) Using a significance level of \(\alpha=0.05\) and \(\mathrm{p}\) -value from (a), state the conclusion in context. (c) Actually, the 10,000 larvae in each group came from a series of 50 different runs of the experiment, with 200 larvae in each group for each run. The researchers believe that conditions dif- fer from run to run, and thus it makes sense to treat each \(\mathrm{run}\) as a case (rather than each fly). In this analysis, we are looking at paired data, and the response variable would be the difference in the number of larvae surviving between the choice group and the no choice group, for each of the 50 runs. The counts (Choice and NoChoice and difference (Choice \(-\) NoChoice) in number of surviving larva are stored in MateChoice. Using the single variable of differences, calculate the p-value for testing whether the average difference is greater than \(0 .\) (Hint: this is a single quantitative variable, so the corresponding test would be for a single mean.) (d) Using a significance level of \(\alpha=0.05\) and the p-value from (c), state the conclusion in context. (e) The experiment being tested in parts (a)-(d) was designed to mimic the experiment from the original study, yet the original study yielded significant results while this study did not. If mate choice really does improve offspring fitness in fruit flies, did the follow-up study being analyzed in parts (a)-(d) make a Type I, Type II, or no error? (f) If mate choice really does not improve offspring fitness in fruit flies, did the original Nature study make a Type I, Type II, or no error?

See all solutions

Recommended explanations on Math Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.