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The proportion of people who live after fighting cancer is \(0.75 .\) Suppose there is a new therapy that is used to increase the survival rate. Use the parameter \(p\) to represent the population portion of people who survive after fighting cancer. For a hypothesis test of the therapy's effectiveness, researchers use a null hypothesis of \(p=0.75\). Pick the correct alternative hypothesis. i. \(p>0.75\) ii. \(p<0.75\) iii. \(p \neq 0.75\)

Short Answer

Expert verified
The correct alternative hypothesis for the given scenario is \(p > 0.75\).

Step by step solution

01

Understand Hypothesis Testing

In a hypothesis test, the null hypothesis represents the status quo or a situation where the variable of interest has no effect. In this case, it represents the scenario where the new therapy does not change the cancer survival rate. The alternative hypothesis presents the scenario we want to test, here that the introduction of the therapy changes the survival rate.
02

Determine the Expected Effect

Since the new therapy is designed to increase the survival rate, the expected effect is that the survival rate is greater than before. Therefore, the survival rate (p) after the introduction of the therapy is expected to be more than 0.75.
03

Identify the Correct Alternative Hypothesis

Based on the expected effect identified in Step 2, the correct alternative hypothesis is that the survival rate (p) after the therapy is greater than 0.75. Therefore, the correct alternative hypothesis is \(p > 0.75\).

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Key Concepts

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

Null Hypothesis
In statistics, the null hypothesis is a fundamental concept in hypothesis testing. It's essentially a starting point or a default assumption. When researchers are conducting a study, like the one in cancer research you’re learning about, they need to have a baseline to compare against.

Here, the null hypothesis is that the new therapy does not make a difference in the survival rate. In other words, it proposes that even after applying the new therapy, the population survival rate remains at 0.75. It's important because it allows scientists to test whether observed data significantly deviate from this baseline, indicating an effect of the therapy.
  • The null hypothesis is denoted as: \( H_0: p = 0.75 \).
  • It's designed to be tested directly; often researchers seek evidence to reject it in favor of an alternative.
If after performing all necessary statistical tests the data support departing from this hypothesis, scientists might then conclude the therapy has an effect.
Alternative Hypothesis
The alternative hypothesis contrasts directly with the null hypothesis, providing the statement researchers hope to support. In our scenario involving cancer research, the alternative hypothesis represents the belief that the new therapy effectively changes the patient survival rate.

The primary goal of establishing it is to determine whether there’s significant evidence that necessitates rejecting the null hypothesis. Researchers are trying to prove if the survival rate after introducing this new therapy is greater than before, implying that it’s indeed effective. Therefore, it’s framed as:
  • The alternative hypothesis is expressed as: \( H_a: p > 0.75 \).
  • This suggests the therapy leads to a survival rate greater than 0.75.
In hypothesis testing, the objective is often to find enough statistical evidence to support this alternative claim, meaning the therapy is effective in increasing survival rates.
Survival Rate
The survival rate is a crucial measure in medical studies, particularly in cancer research. It refers to the proportion of patients who continue to live after a specified time post-treatment. A higher survival rate implies better treatment effectiveness and patient outcomes.

For patients dealing with cancer, understanding and improving survival rates can have profound implications for treatment strategies and quality of life. The initial survival rate in our problem is stated to be 0.75, meaning 75% of patients survived up to the last check. In studies involving new therapies, such as the one described:
  • Researchers aim to measure if treatments lead to an increased survival rate.
  • An increased rate signals a positive response to therapy efforts and guides future treatment standards.
These rates help in not just evaluating individual therapies but also in broader healthcare planning and resource allocation.
Cancer Research
Cancer research is a vital field within medical science focused on understanding and treating cancer. It involves testing new therapies and methodologies to improve patient survival rates and the quality of life during and after treatment.

The introduction of a new therapy, as mentioned in the exercise, is part of ongoing efforts to enhance treatment efficacy. Research in this area typically involves:
  • Conducting clinical trials to test the safety and effectiveness of new treatments.
  • Analyzing survival rates to determine the benefits of new interventions.
  • Monitoring outcomes to adapt and improve treatment protocols.
Cancer research not only seeks to increase survival rates but also aims to reduce side effects and make treatments accessible to more patients. Continued innovation and testing through projects like these are imperative for the advancement of medical science and patient care.

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Most popular questions from this chapter

Standard anticoagulant therapy (to prevent blood clots) requires frequent laboratory monitoring to prevent internal bleeding. A new procedure using rivaroxaban (riva) was tested because it does not require frequent monitoring. A randomized trial (Einstein-PE Investigators 2012 ) was carried out, with standard therapy being randomly assigned to half of 4832 patients and riva randomly assigned to the other half. A bad result was recurrence of a blood clot in a vein. Fifty of the 2416 patients on standard therapy had a bad outcome, and 44 of the 2416 patients on riva had a bad outcome. a. Test the hypothesis that the proportions of bad results are different for riva and standard therapy patients. Use a significance level of \(0.05\), and show all four steps. b. Using methods leamed in Chapter 7 , estimate the difference between the two population proportions using a \(95 \%\) confidence interval, and comment on how it can be used to evaluate the null hypothesis in part a.

When comparing two sample proportions with a two-sided alternative hypothesis, all other factors being equal, will you get a smaller p-value with a larger sample size or a smaller sample size? Explain.

A proponent of a new proposition on a ballot wants to know whether the proposition is likely to pass. Suppose a poll is taken, and 580 out of 1000 randomly selected people support the proposition. Should the proponent use a hypothesis test or a confidence interval to answer this question? Explain. If it is a hypothesis test, state the hypotheses and find the test statistic, p-value, and conclusion. If a confidence interval is appropriate, find the approximate \(95 \%\) confidence interval. In both cases, assume that the necessary conditions have been met.

The Gallup organization frequently conducts polls in which they ask the following question: "In general, do you feel that the laws covering the sale of firearms should be made more strict, less strict, or kept as they are now?" In February \(1999,60 \%\) of those surveyed said "more strict," and on April 26,1999, shortly after the Columbine High School shootings, \(66 \%\) of those surveyed said "more strict." a. Assume that both polls used samples of 560 people. Determine the number of people in the sample who said "more strict" in February 1999 , before the school shootings, and the number who said "more strict" in late April 1999 , after the school shootings. b. Do a test to see whether the proportion that said "more strict" is statistically significantly different in the two different surveys, using a significance level of \(0.01\). c. Repeat the problem, assuming that the sample sizes were both 1120 . d. Comment on the effect of different sample sizes on the \(\mathrm{p}\) -value and on the conclusion.

Suppose we are testing people to see whether the rate of use of seat belts has changed from a previous value of \(88 \%\). Suppose that in our random sample of 500 people we see that 450 have the seat belt fastened. Which of the following figures has the correct p-value for testing the hypothesis that the proportion who use seat belts has changed? Explain your choice.

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