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In a survey of 1,000 women ages 22 to 35 who work full-time, 540 indicated that they would be willing to give up some personal time in order to make more money (USA Today, March 4, 2010). The sample was selected to be representative of women in the targeted age group. a. Do the sample data provide convincing evidence that a majority of women ages 22 to 35 who work fulltime would be willing to give up some personal time for more money? Test the relevant hypotheses using \(\alpha=0.01\) b. Would it be reasonable to generalize the conclusion from Part (a) to all working women? Explain why or why not.

Short Answer

Expert verified
a. Yes, the sample data does provide convincing evidence that a majority of women ages 22 to 35 who work fulltime would be willing to give up some personal time for more money, as the p-value is less than 0.01. b. It would not be reasonable to generalize this to all working women, as the sample specifically includes only full-time workers within a certain age group, who may have different preferences compared to part-time workers or those in different age groups.

Step by step solution

01

Formulating the Hypotheses

The null hypothesis is that the majority (more than 0.5) of women ages 22 to 35 who work full time are not willing to give up personal time for more money, which can be written as H0: \(p \leq 0.5\). The alternative hypothesis, which we are testing for, is that the majority will give up personal time for more money, or H1: \(p > 0.5\).
02

Calculating the Test Statistic

The test statistic is calculated using the formula \((\hat{p} - p_0) / \sqrt{p_0(1 - p_0) / n}\), where \(\hat{p}\) is the sample proportion, \(p_0\) is the assumed population proportion, and \(n\) is the sample size. In this case, \(\hat{p} = 540/1000 = 0.54\), \(p_0 = 0.5\), and \(n = 1000\). Plugging these values into the test statistic formula gives a test statistic roughly equal to 2.83.
03

The p-value

The p-value, which represents the chance of obtaining a test statistic as extreme or more extreme than what was actually observed in case the null hypothesis is true, is calculated using the normal distribution. Given that our test in this case is one-tailed (with the alternate hypothesis suggesting that \(p > 0.5\)), we calculate the p-value as the probability of getting a value as extreme or more than our test statistic in the tail of the distribution. Considering the test statistic 2.83, the p-value will be smaller than \(\alpha=0.01\), typically found in normal distribution tables or by using software.
04

Conclusion of the Hypothesis Test

As the p-value obtained is less than the level of significance \(\alpha = 0.01\), the null hypothesis is rejected, providing convincing evidence that a majority of women ages 22 to 35 who work full time are willing to give up some personal time for more money.
05

Generalizability

While it might be tempting to generalize this result to all working women, it might not be reasonable to do so. The reason is that the sample was selected specifically from women ages 22 to 35 who work full time. This group may have different preferences and pressures compared to other working women such as part-time workers or those of different age groups, thus generalizing may lead to biased or wrongly inferred conclusions.

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Key Concepts

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

Sample Proportion
Sample proportion is a key concept in hypothesis testing. It is the proportion of subjects or objects in a sample that exhibit a particular trait. In our given problem, the sample proportion, denoted as \( \hat{p} \), refers to the fraction of surveyed women who are willing to give up personal time for more money. Let's break this down:
  • Number of women surveyed: 1,000
  • Number willing to give up personal time: 540
To find the sample proportion, we calculate: \[ \hat{p} = \frac{540}{1000} = 0.54 \] This means 54% of the sampled women agreed to sacrifice personal time for more money. The sample proportion forms the basis for testing claims about the population parameter.
P-value
The p-value is an essential part of hypothesis testing as it helps to determine the significance of your results. A p-value reflects the probability that the observed difference or a more extreme difference would occur by chance if the null hypothesis were true. In our case, we calculated a test statistic of 2.83 from the sample data.Here's how the p-value helps:
  • It assesses how extreme the observed data are, assuming the null hypothesis is true.
  • A smaller p-value indicates stronger evidence against the null hypothesis.
Given our test statistic, the p-value is less than the significance level of \( \alpha = 0.01 \). This small p-value suggests that such a result is highly unlikely to occur by random chance, thus rejecting the null hypothesis in favor of the alternative.
Null Hypothesis
The null hypothesis is the default position in hypothesis testing that there is no effect or no difference. It serves as a starting assumption for statistical testing. In the problem at hand, the null hypothesis (denoted as \( H_0 \)) states that the population proportion of women willing to give up personal time does not exceed 0.5, expressed as \( p \leq 0.5 \).Here's why the null hypothesis is crucial:
  • It provides a baseline to measure evidence against.
  • It's usually set up to reflect the status quo or no change condition.
In our example, rejecting the null hypothesis after conducting the test implies significant data supporting the claim that more than half of the women would give up their personal time for more money.
Generalizability
Generalizability refers to the extent to which the findings from a study can be applied to other settings, populations, or situations. In this example, one might wonder if the conclusion that a majority of surveyed women will sacrifice personal time for money can be applied to all working women. However, generalizability has its limitations: - The sample only includes women aged 22 to 35 working full-time. - Different age groups, employment types, or demographics might exhibit different behaviors. Thus, while the study's results are valid for the specific group surveyed, caution is necessary before applying these results universally to all working women. It's vital to recognize the population from which the sample was drawn to avoid erroneous generalizations.

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