Math Problem Statement

You are conducting a multinomial Goodness of Fit hypothesis test for the claim that the 4 categories occur with the following frequencies: Ho Pa=0.1; Pb =0.3; Pc= 0.5 ; Pd =0.1

Complete the table. Report all answers accurate to three decimal places. Category Observed Frequency Expected Frequency A 33 B 43 C 44 D 16 What is the chi-square test-statistic for this data? (2 decimal places) xsqared

What is the P-Value? (3 decimal places) P-Value =

For significance level alpha 0.005,

What would be the conclusion of this hypothesis test? Fail to reject the Null Hypothesis Reject the Null Hypothesis

Report all answers accurate to three decimal places. Question HelpQuestion 2: Video1

Solution

To solve this problem, we will compute the chi-square test statistic (χ2\chi^2) and p-value for the hypothesis test. Here are the steps:


Step 1: Calculate Expected Frequencies

The expected frequency for each category is calculated using the formula: Expected Frequency=(Total Observations)×(Expected Proportion)\text{Expected Frequency} = (\text{Total Observations}) \times (\text{Expected Proportion})

Step 2: Compute the Chi-Square Test Statistic

The chi-square test statistic is given by: χ2=(Observed FrequencyExpected Frequency)2Expected Frequency\chi^2 = \sum \frac{(\text{Observed Frequency} - \text{Expected Frequency})^2}{\text{Expected Frequency}}

Step 3: Determine the P-Value

Using the chi-square distribution with k1k - 1 degrees of freedom (where kk is the number of categories), compute the p-value.

Step 4: Compare the P-Value to the Significance Level

Decide whether to reject or fail to reject H0H_0 based on the comparison of p-value to α=0.005\alpha = 0.005.


Step-by-Step Calculation

1. Observed and Expected Frequencies

Let’s compute the expected frequencies for each category:

  • Total Observations: 33+43+44+16=13633 + 43 + 44 + 16 = 136
CategoryObserved (O)Proportion (P)Expected (E) = 136×P136 \times P
A330.1136×0.1=13.6136 \times 0.1 = 13.6
B430.3136×0.3=40.8136 \times 0.3 = 40.8
C440.5136×0.5=68.0136 \times 0.5 = 68.0
D160.1136×0.1=13.6136 \times 0.1 = 13.6

2. Chi-Square Test Statistic

χ2=(OE)2E\chi^2 = \sum \frac{(O - E)^2}{E}

CategoryOE(OE)2(O - E)^2(OE)2E\frac{(O - E)^2}{E}
A3313.6(3313.6)2=372.1(33 - 13.6)^2 = 372.1372.113.6=27.35\frac{372.1}{13.6} = 27.35
B4340.8(4340.8)2=4.84(43 - 40.8)^2 = 4.844.8440.8=0.12\frac{4.84}{40.8} = 0.12
C4468.0(4468.0)2=576.0(44 - 68.0)^2 = 576.0576.068.0=8.47\frac{576.0}{68.0} = 8.47
D1613.6(1613.6)2=5.76(16 - 13.6)^2 = 5.765.7613.6=0.42\frac{5.76}{13.6} = 0.42

Summing these: χ2=27.35+0.12+8.47+0.42=36.36\chi^2 = 27.35 + 0.12 + 8.47 + 0.42 = 36.36

3. Degrees of Freedom and P-Value

Degrees of freedom (df\text{df}) = k1=41=3k - 1 = 4 - 1 = 3.

Using a chi-square table or calculator, for χ2=36.36\chi^2 = 36.36 and df=3\text{df} = 3, we find:

P-Value<0.001\text{P-Value} < 0.001

4. Hypothesis Test Conclusion

At α=0.005\alpha = 0.005, P-Value<α\text{P-Value} < \alpha, so we reject the null hypothesis.


Final Answers

  1. χ2=36.36\chi^2 = 36.36 (2 decimal places)
  2. P-Value <0.001< 0.001 (3 decimal places)
  3. Conclusion: Reject the Null Hypothesis

Would you like to see the detailed steps or calculations for p-values? Let me know! 😊


Here are 5 follow-up questions:

  1. What would happen if the sample size increased?
  2. How does changing the significance level (α\alpha) affect the hypothesis test?
  3. Why is it necessary to calculate degrees of freedom?
  4. How does the chi-square test differ from other goodness-of-fit tests?
  5. Can this method be applied to continuous data?

Tip: Always double-check observed and expected frequencies for accuracy in hypothesis testing.

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Math Problem Analysis

Mathematical Concepts

Goodness of Fit Test
Chi-Square Distribution
Hypothesis Testing

Formulas

Expected Frequency = Total Observations × Expected Proportion
Chi-Square Test Statistic: χ² = Σ((Observed - Expected)² / Expected)

Theorems

Chi-Square Goodness of Fit Test Theorem

Suitable Grade Level

Grades 11-12 or introductory college statistics