/*! 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 48 The article referenced in the pr... [FREE SOLUTION] | 91Ó°ÊÓ

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The article referenced in the previous exercise also reported that \(24 \%\) of the males and \(16 \%\) of the females in the 2006 sample reported owning an MP3 player. Suppose that there were the same number of males and females in the sample of 1112 . Do these data provide convincing evidence that the proportion of females that owned an MP3 player in 2006 is smaller than the corresponding proportion of males? Carry out a test using a significance level of 01 .

Short Answer

Expert verified
To answer this exercise, calculate the test statistic and p-value from the given data. If the p-value is less than the significance level (0.01), then there is convincing evidence supporting the hypothesis that the proportion of females that owned an MP3 player in 2006 is smaller than that of males. If the p-value is greater than or equal to the significance level, then there is not sufficient evidence to support this claim. The exact answer will depend on the calculated values.

Step by step solution

01

Identify the hypothesis

In this problem, we are testing whether the proportion of females owning an MP3 players is lesser than males. The null hypothesis would be that the proportions are equal, while the alternative hypothesis is that the proportion of females is less than that of males. Hence, \(H_0: p_f = p_m\) (the proportion of females is equal to the proportion of males) and \(H_1: p_f < p_m\) (the proportion of females is less than the proportion of males).
02

Calculate the test statistic

The test statistic is calculated using the formula \( Z = \frac{ \hat{p_f} - \hat{p_m}}{ \sqrt{ \hat{p} (1- \hat{p}) ( \frac{1}{n_f} + \frac{1}{n_m}) } }\) where \(\hat{p}\) is the pooled sample proportion, calculated as \(\hat{p} = \frac{x_f + x_m}{n_f + n_m}\). \(x_f\), \(x_m\), \(n_f\) and \(n_m\) represent the number of successful outcomes (owning an MP3 player) and total number of trials for females and males respectively. Here, \(n_f = n_m = 1112 / 2 = 556\) and \(x_f = 0.16 \times 556 = 89\), \(x_m = 0.24 \times 556 = 133.44\). Plugging these into the formula will yield the test statistic.
03

Calculate the p-value

The p-value is the probability of getting the observed statistic, or a more extreme value, if the null hypothesis is true. In this case, as it is a one-sided test, the p-value is the probability of getting this Z score or more extreme (lesser, as per our alternative hypothesis). This can be calculated from standard normal distribution tables or with a calculator that has this functionality.
04

Interpret the results

If the p-value is less than the significance level (0.01 in this problem), then we reject the null hypothesis and conclude that there is convincing evidence that the proportion of females that owned an MP3 player in 2006 is smaller than the corresponding proportion of males. However, if the p-value is greater than or equal to the significance level, we fail to reject the null hypothesis and conclude that there is not enough evidence to support the claim that the proportion of females that owned an MP3 player in 2006 is smaller than the corresponding proportion of males.

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Key Concepts

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

Proportion Comparison
When conducting a hypothesis test involving proportions, the aim is to determine if there is a significant difference between two groups. In this problem, we're comparing the proportion of males and females owning MP3 players in 2006. The first step is to clearly identify the proportions being compared:- Male Proportion (\( \hat{p_m} \)): 24%- Female Proportion (\( \hat{p_f} \)): 16%Our goal is to assess whether the proportion of females is significantly less than that of males. This involves setting up two hypotheses:- Null Hypothesis (\( H_0 \)): The proportions are equal (\( p_f = p_m \))- Alternative Hypothesis (\( H_1 \)): The proportion of females is less than males (\( p_f < p_m \))Using hypothesis testing for proportion comparisons allows us to objectively decide if the observed difference is likely due to a real effect or just random chance.
Significance Level
The significance level is a threshold for determining whether a result is statistically significant. It's like a cut-off point in deciding if you should believe the results of your hypothesis test. For this problem, the significance level is set at 0.01.Some key points to understand significance level include:- It is denoted as \( \alpha \).- A common choice for \( \alpha \) is 0.05, but more stringent tests use 0.01 or even 0.001.- A lower \( \alpha \) means you need more convincing evidence to reject the null hypothesis.In practice, a significance level of 0.01 implies a 1% risk of concluding that a difference exists when there is no real difference. This means the decision rule is: if the computed p-value is less than 0.01, we reject the null hypothesis, concluding that the evidence supports the alternative hypothesis.
P-value Calculation
The p-value helps to measure the strength of evidence against the null hypothesis. It tells us the probability of observing a test statistic as extreme as, or more extreme than, the one actually observed, given that the null hypothesis is true.Here’s how you interpret the p-value:- A smaller p-value indicates stronger evidence against the null hypothesis.- For example, if the p-value is computed and found to be less than the significance level of 0.01, it suggests rejecting the null hypothesis.To calculate it, you need:- The test statistic, determined from the formula: \[ Z = \frac{ \hat{p_f} - \hat{p_m}}{ \sqrt{ \hat{p} (1- \hat{p}) ( \frac{1}{n_f} + \frac{1}{n_m}) } } \]- Making use of a standard normal distribution to find the probability of obtaining a Z value as extreme as the computed one under the null hypothesis.Ultimately, the p-value helps decide if the observed data aligns with the null hypothesis or if we have sufficient reason to believe the alternative hypothesis. In this case, it aids in establishing whether fewer females owned MP3 players compared to males.

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