/*! 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 11 A researcher looking for evidenc... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

A researcher looking for evidence of extrasensory perception (ESP) tests 1000 subjects. Nine of these subjects do significantly better \((P<0.01)\) than random guessing. (a) Nine seems like a lot of people, but you can't conclude that these nine people have ESP. Why not? (b) What should the researcher now do to test whether any of these nine subjects have ESP?

Short Answer

Expert verified
Nine results are expected by chance (at \(P<0.01\)). Conduct repeated tests for consistency.

Step by step solution

01

Understanding Significance Level

When testing for extrasensory perception (ESP) in 1000 subjects, a significance level of \(P<0.01\) means there is a less than 1% probability that the result is due to random chance. This threshold is used to determine statistical significance. However, achieving this statistical significance does not inherently prove the existence of ESP.
02

Calculating Expected Random Success Rate

Given the significance level of \(P<0.01\), out of 1000 tests, it is expected that about 10 tests could result in statistical significance purely by random chance. Therefore, finding 9 individuals who perform significantly better than random guessing is consistent with the expected random results.
03

Understanding the False Positive Rate

Nine individuals showing significant results might seem substantial; however, according to the 1% significance level, these results could likely be false positives. This means these successes might have occurred purely due to chance rather than true ESP capabilities.
04

Planning a Follow-Up Study

To better ascertain whether these nine individuals truly have ESP abilities, the researcher should conduct further investigations. This could involve repeating the test under tighter controls, possibly with a larger sample size or different methodology, to see if these individuals consistently outperform chance.
05

Evaluating Consistency and Validity

In follow-up tests, the researcher should check if the same individuals consistently show significant results. Employing different types of ESP tests might also help in ruling out any biases or errors from the initial test method.

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.

Extrasensory Perception
Extrasensory perception, or ESP, refers to the ability to gain information through means other than the known human senses. Think of it as having a 'sixth sense' that allows someone to perceive things that others cannot via the normal sensory channels.
Despite being a fascinating subject, ESP remains controversial and widely debated in the scientific community due to the lack of consistent and verifiable evidence supporting its existence.
When researchers set out to study ESP, they often conduct experiments in controlled settings to measure if certain individuals can demonstrate this ability beyond what is expected by chance alone. Positive results in such studies, especially those statistically significant, are sometimes interpreted as indicative of ESP. However, due to the complexity and potential biases in experiments, a single study's result isn't sufficient to prove ESP is real.
False Positive Rate
The concept of a false positive rate is crucial in understanding experimental results, especially in ESP research. A false positive occurs when a test incorrectly indicates the presence of a condition—in this case, ESP—when it is not present.
This happens due to the random variation in data or errors in testing methods.
In statistical testing, a specified significance level, such as 0.01, represents a 1% false positive rate.
This means there's a 1% chance that any significant result is due to random chance rather than a true effect.
  • With 1000 subjects and a significance level of 0.01, it is statistically expected that roughly 10 findings might appear significant by chance alone, even if ESP was not present.
  • In this context, discovering nine subjects out of 1000 who seem to have ESP qualities could still be a fluke, thus classified as false positives.
Follow-Up Study
After initial results suggest some indication of ESP, conducting a follow-up study becomes essential to determine the true nature of the findings. A follow-up study involves re-evaluating the same individuals under more controlled or varied conditions to verify if the results were genuine or occurred randomly.
Significant outcomes that repeatedly appear in follow-up studies with different parameters or methodologies are more likely to indicate true effects rather than chance occurrences.
Additionally, a follow-up study could include:
  • Increasing the sample size to reduce random variations.
  • Altering the testing setup to eliminate any biases or artifacts from the original study.
  • Implementing a double-blind procedure to prevent experimenter bias.
All these strategies enhance the reliability and validity of the results obtained.
Random Chance
Random chance can play a significant role in scientific research and contribute to unexpected results. In the context of an ESP study involving multiple subjects, random chance refers to occurrences statistically expected to happen even without a real effect present.
Researchers often use probability and statistical methods to understand the impact of random chance. The role of random chance can be especially notable when testing large numbers of subjects, as some results will inevitably meet the criteria for statistical significance merely by luck.
Understanding and accounting for random chance is pivotal. It helps prevent the misinterpretation of random results as meaningful discoveries. When assessing claims of ESP, or any scientific claim, differentiating between results due to random chance and those of genuine phenomena is fundamental.

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

A market researcher chooses at random from women entering a large upscale department store. One outcome of the study is a \(95 \%\) confidence interval for the mean of "the highest price you would pay for a handbag." (a) Explain why this confidence interval does not give useful information about the population of all women. (b) Explain why it may give useful information about the population of women who shop at large upscale department stores.

A college administrator questions the first 50 students he meets on campus the day after final exams are over. He asks them whether they had positive, neutral, or negative overall feelings about the term that had just ended. Suggest some reasons it may be risky to act as if the first 50 students at this particular time are an SRS of all students at this college.

How sensitive are the untrained noses of students? Exercise \(16.27\) (page 390) gives the lowest levels of dimethyl sulfide (DMS) that 10 students could detect. You want to estimate the mean DMS odor threshold among all students and you would be satisfied to estimate the mean to within \(\pm 0.1\) with \(99 \%\) confidence. The standard deviation of the odor threshold for untrained noses is known to be \(\sigma=7\) micrograms per liter of wine. How large an SRS of untrained students do you need?

Which of the following questions does a test of significance answer? Briefly explain your replies. (a) Is the sample or experiment properly designed? (b) Is the observed effect due to chance? (c) Is the observed effect important?

A survey of licensed drivers inquired about running red lights. One question asked, "Of every 10 motorists who run a red light, about how many do you think will be caught?" The mean result for 880 respondents was \(\mathrm{x}^{-} \bar{x}\) \(=1.92\) and the standard deviation was \(s=1.83 .{ }^{2}\) For this large sample, \(s\) will be close to the population standard deviation \(\sigma\), so suppose we know that \(\sigma=1.83\). (a) Give a 95\% confidence interval for the mean opinion in the population of all licensed drivers. (b) The distribution of responses is skewed to the right rather than Normal. This will not strongly affect the \(z\) confidence interval for this sample. Why not? (c) The 880 respondents are an SRS from completed calls among 45,956 calls to randomly chosen residential telephone numbers listed in telephone directories. Only 5029 of the calls were completed. This information gives two reasons to suspect that the sample may not represent all licensed drivers. What are these reasons?

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.