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Myers-Briggs: Extroverts Are most student government leaders extroverts? According to Myers-Briggs estimates, about \(82 \%\) of college student government leaders are extroverts (Source: Myers -Briggs Type Indicator Atlas of Type Tables). Suppose that a Myers-Briggs personality preference test was given to a random sample of 73 student government leaders attending a large national leadership conference and that 56 were found to be extroverts. Does this indicate that the population proportion of extroverts among college student government leaders is different (either way) from \(82 \% ?\) Use \(\alpha=0.01.\)

Short Answer

Expert verified
No, there's no significant evidence to prove the proportion differs from 82%.

Step by step solution

01

Define the Hypotheses

We are conducting a hypothesis test about the proportion of extroverts among college student government leaders. The null hypothesis (\(H_0\)) is that the population proportion of extroverts is \(p = 0.82\). The alternative hypothesis (\(H_a\)) is that the population proportion is different from \(0.82\). Thus, \(H_0: p = 0.82\) and \(H_a: p eq 0.82\).
02

Determine the Test Statistic

We use the formula for the test statistic for a proportion: \[ z = \frac{\hat{p} - p_0}{\sqrt{\frac{p_0(1-p_0)}{n}}} \] where \(\hat{p}\) is the sample proportion, \(p_0\) is the hypothesized population proportion, and \(n\) is the sample size. Calculate \(\hat{p}\) as follows: \[ \hat{p} = \frac{56}{73} \approx 0.767123 \] Thus, the test statistic becomes: \[ z = \frac{0.767123 - 0.82}{\sqrt{\frac{0.82 \times 0.18}{73}}} \]
03

Calculate the Test Statistic

Substitute the values into the formula:\[ z = \frac{0.767123 - 0.82}{\sqrt{\frac{0.82 \times 0.18}{73}}} \approx \frac{-0.052877}{\sqrt{0.002025}} \approx \frac{-0.052877}{0.044994} \approx -1.175 \] Thus, the calculated test statistic is approximately \(-1.175\).
04

Determine the Critical Values and Decision Rule

Since this is a two-tailed test with \( \alpha = 0.01 \), we look up the critical values in the standard normal distribution table for \( \alpha/2 = 0.005 \). These correspond to \( z \approx \pm 2.576 \). The decision rule is to reject the null hypothesis if \( z < -2.576 \) or \( z > 2.576 \).
05

Make the Decision

The calculated test statistic is \(-1.175\), which is not less than \(-2.576\) and not greater than \(2.576\). Therefore, we do not reject the null hypothesis at the \(0.01\) significance level.
06

State the Conclusion

There is not enough statistical evidence to conclude that the proportion of extroverts among college student government leaders is different from \(82\%\) at the \(0.01\) level of significance.

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Key Concepts

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

Myers-Briggs Type Indicator
The Myers-Briggs Type Indicator (MBTI) is a popular tool used to categorize people's personality traits.
Developed by Isabel Briggs Myers and Katherine Cook Briggs, the test sorts individuals into 16 different personality types based on four dichotomies. These include:
  • Introversion vs. Extroversion
  • Sensing vs. Intuition
  • Thinking vs. Feeling
  • Judging vs. Perceiving
The MBTI is widely used in various settings to understand behavioral tendencies and preferences.
This can be beneficial in educational and organizational environments to improve teamwork and communication. In the context of student government leaders, identifying extroverts through the MBTI can provide insights into leadership styles and preferences.
Population Proportion
The concept of population proportion refers to the fraction of a population that exhibits a certain trait or characteristic.
In statistical analysis, determining the precise proportion of a particular attribute within a population is important for making generalizations and predictions.
In our exercise, the focus is on the proportion of college student government leaders who are extroverts, reported by MBTI to be 82%.
This is an example of how population proportion provides a standardized measure to compare different subgroups within a larger group. Calculating the sample proportion involves dividing the number of individuals with the characteristic by the total sample size. For instance, in our sample of 73 leaders, 56 were extroverts, giving us a sample proportion of
  • Calculated as: \(\hat{p} = \frac{56}{73} \approx 0.767123\)
Understanding these calculations and their implications helps in assessing whether sample findings significantly differ from established population figures.
Test Statistic
In hypothesis testing, a test statistic is a standardized value derived from sample data.
This is used to decide whether to support or reject the null hypothesis.
The test statistic compares your observed data with what is expected under the assumed null hypothesis.
For our specific scenario, the formula employed is: \[z = \frac{\hat{p} - p_0}{\sqrt{\frac{p_0(1-p_0)}{n}}}\] This formula helps transform the data into a form that is understandable by relating it to the standard normal distribution.
  • Where \(\hat{p}\) is the sample proportion, \(p_0\) is the hypothesized population proportion, and \(n\) is the sample size.
Once computed, the test statistic value indicates how many standard deviations our sample proportion is from the hypothesized proportion. In our exercise, the calculated test statistic is approximately -1.175, suggesting the sample data isn't far enough from the assumed population mean of 0.82 to warrant rejecting the null hypothesis.
Significance Level
The significance level, denoted by \(\alpha\), is a threshold used in hypothesis testing to determine whether the results are statistically significant.
In simpler terms, it defines the probability of rejecting the null hypothesis when it is actually true.A common choice is \(\alpha = 0.05\), but for more stringent tests like our exercise, \(\alpha = 0.01\) is used. This means there's only a 1% chance of incorrectly rejecting a true null hypothesis.In our hypothesis test concerning student government leaders:
  • We have a two-tailed test since we want to see if there is a difference from 82%, either higher or lower.
  • The critical z-values at a 0.01 significance level are approximately \(\pm 2.576\).
These values define the range where the null hypothesis must be rejected. If the test statistic falls outside this range, the null hypothesis is rejected.
In this exercise, the test statistic was -1.175, which did not exceed the critical range, leading us to uphold the null hypothesis.

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