/*! 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 37 Why Are Larger Samples Better? S... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

Why Are Larger Samples Better? Statisticians prefer large samples. Describe briefly the effect of increasing the size of a sample (or the number of subjects in an experiment) on each of the following: a. The P-value of a test, when \(H_{0}\) is false and all facts about the population remain unchanged as \(\pi\) increases b. (Optional) The power of a fixed level \(\alpha\) test, when \(\alpha\), the alternative hypothesis, and all facts about the population remain unchanged

Short Answer

Expert verified
Larger samples make detecting true effects more likely, reducing P-values and increasing test power.

Step by step solution

01

Understand Sample Size Impact on P-Value

In hypothesis testing, a P-value indicates the probability of observing the test results under the null hypothesis, assuming it is true. As the sample size (\(n\)) increases, the test statistics become more stable and less influenced by sample variability, making it easier to detect true effects. Thus, if the null hypothesis (\(H_0\)) is false, a larger sample size makes it more likely to obtain a smaller P-value, indicating that the observed effect isn't due to random chance.
02

Understand Sample Size Impact on Test Power

The power of a statistical test is the probability of correctly rejecting the null hypothesis (\(H_0\)) when it is false. This is influenced by the sample size, significance level (\(\alpha\)), and effect size. As the sample size increases, the test's sensitivity to detect an actual effect increases, thereby increasing the test's power. This means that with a larger sample, the probability of identifying a true effect rises, reducing the risk of a Type II error (failing to reject a false \(H_0\)).

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.

P-value
The P-value is a crucial concept in statistics that helps us make decisions based on data. It measures the strength of the evidence against the null hypothesis. A smaller P-value suggests stronger evidence to reject the null hypothesis. When the null hypothesis (\(H_0\)) is false, a large sample can help reveal the truth by decreasing the P-value.

Increasing the sample size makes statistical tests more reliable. It reduces the impact of random errors and sample variability. This means that if \(H_0\) is false, larger samples are more likely to show this by producing smaller P-values. This is because the additional data gives a clearer picture of the population, making it easier to detect true differences or effects.

In summary, larger samples can lead to more convincing P-values, which in turn provides stronger evidence in rejecting a false null hypothesis.
Hypothesis Testing
Hypothesis testing is a statistical method used to determine if there is enough evidence to reject a null hypothesis. It involves comparing observed results with the results we'd expect if the null hypothesis were true.

The process starts with forming two hypotheses: the null hypothesis (\(H_0\)), which represents no effect or status quo, and the alternative hypothesis (\(H_1\)), which represents the change or effect we theorize. After collecting sample data, statistical tests are used to calculate the P-value, which helps in deciding whether to reject \(H_0\).

Larger samples can make hypothesis testing more effective by providing more accurate estimates of population parameters. This increased accuracy makes the findings more credible and reduces the likelihood of misleading conclusions. It's important to note that hypothesis testing can never prove \(H_0\); it can only suggest that it might be false.
Statistical Power
Statistical power is the probability that a test will correctly reject a false null hypothesis. It is a measure of a test's ability to detect an effect when one truly exists. A higher power means a lower chance of missing a true effect, which is desirable in experiments and studies.

One of the main factors influencing statistical power is sample size. Larger samples generally result in higher power because they provide clearer insights and more precise estimates of the population. This increased precision means tests are more sensitive to detect actual effects or differences.

In practical terms, higher power reduces the chances of committing a Type II error, where a false null hypothesis is not rejected. Researchers often aim for a power of at least 80%, which means there's a good chance the test will uncover any true effects.
Type II Error
A Type II error occurs when a statistical test fails to reject a false null hypothesis. In simple terms, it means that there's an effect or difference present, but the test didn't detect it.

Increasing the sample size can help reduce the probability of making a Type II error. Larger samples provide more information and increase the test's power, making it more likely to identify true effects. The risk of a Type II error decreases as the sample size increases, improving the reliability of the conclusions drawn from the test.

While researchers strive to minimize Type II errors, balancing the risk can be challenging. It requires careful planning of the sample size along with considering the Type I error (rejecting a true null hypothesis). Being aware of these errors is crucial for drawing accurate conclusions in research and experiments.

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

Two Types of Error. Your company markets a computerized medical diagnostic program used to evaluate thousands of people. The program scans the results of routine medical tests (pulse rate, blood tests, etc.) and refers the case to a doctor if there is evidence of a medical problem. The program makes a decision about each person. a. What are the two hypotheses and the two types of error that the program can make? Describe the two types of error in terms of false-positive and false- negative test results. b. The program can be adjusted to decrease one error probability, at the cost of an increase in the other error probability. Which error probability would you choose to make smaller, and why? (This is a matter of judgment. There is no single correct answer.)

You visit the online Harris Interactive Poll. Based on 2223 responses, the poll reports that \(60 \%\) of U.S. adults believe that chef is a prestigious occupation. - You should refuse to calculate a \(95 \%\) confidence interval for the proportion of all U.S. adults who believe chef is a prestigious occupation based on this sample because a. this percentage is too small. b. inference from a voluntary response sample can't be trusted. c. the sample is too large.

Is It Significant? In the absence of special preparation, SAT Mathematics (SATM) scores in 2019 varied Normally with mean \(\mu=528\) and \(\sigma=117\). Fifty students go through a rigorous training program designed to raise their SATM scores by improving their mathematics skills. Either by hand or by using the P-Value of a Test of Significance applet, carry out a test of $$ \begin{aligned} &H_{0}: \mu=528 \\ &H_{a}: \mu>528 \end{aligned} $$ (with \(\sigma=117\) ) in each of the following situations: a. The students' average score is \(x=555\). Is this result significant at the \(5 \%\) level? b. The average score is \(x=556\). Is this result significant at the \(5 \%\) level? The difference between the two outcomes in parts \((a)\) and (b) is of no practical importance. Beware attempts to treat \(\alpha=0.05\) as sacred.

Error Probabilities. You read that a statistical test at significance level \(\alpha=0.05\) has power \(0.80\). What are the probabilities of Type I and Type Il errors for this test?

How Far Do Rich Parents Take Us? How much education children get is strongly associated with the wealth and social status of their parents. In social science jargon, this is socioeconomic status, or SES. But the SES of parents has little influence on whether children who have graduated from college go on to yet more education. One study looked at whether college graduates took the graduate admissions tests for business, law, and other graduate programs. The effects of the parents' SES on taking the LSAT for law school were "both statistically insignificant and small" a. What does "statistically insignificant" mean? b. Why is it important that the effects were small in size as well as insignificant?

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.