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Topic 7 Homework (Nonadaptive) Question 12 of 16 (1 point)|Question Attempt: 1 of Unlimited

Dennis

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Question 12 The following contingency table gives a summary of the data from 2000 trials of a visual experiment. Each of the trials was classified according to two variables: color vision of the participant ("Colorblind" or "Not colorblind") and trial outcome ("Hit", "Miss", "False alarm", or "Correct rejection"). In the cells of the table are the respective observed frequencies, and three of the cells also have blanks. Fill in these blanks with the frequencies expected if the two variables, color vision of participant and trial outcome, are independent. Round your answers to two or more decimal places.

Send data to Excel Trial outcome Hit Miss False alarm Correct rejection Total Color vision of participant Colorblind 77

22 23

70

192 Not colorblind 630 269 271 638 1808 Total 707 291 294 708 2000

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Solution

In this question, we are asked to fill in the blanks of the contingency table with the expected frequencies if the two variables (color vision of the participant and trial outcome) are independent.

The key to solving this is to use the formula for the expected frequency in a contingency table, which is:

Expected Frequency=(Row Total)×(Column Total)Grand Total\text{Expected Frequency} = \frac{(\text{Row Total}) \times (\text{Column Total})}{\text{Grand Total}}

Here is a step-by-step guide:

Step 1: Set up the contingency table

We are given the following table:

Trial OutcomeHitMissFalse AlarmCorrect RejectionTotal
Colorblind772223___192
Not Colorblind6302692716381808
Total7072912947082000

We are missing the "Correct Rejection" value for colorblind participants, and the "Hit" and "Miss" values for not colorblind participants.

Step 2: Apply the expected frequency formula

Let's fill in the blanks.

1. For "Colorblind - Correct Rejection":

Expected Frequency (Colorblind - Correct Rejection)=(192×708)2000=1359362000=67.968\text{Expected Frequency (Colorblind - Correct Rejection)} = \frac{(192 \times 708)}{2000} = \frac{135936}{2000} = 67.968 Rounded to two decimal places, the expected frequency is 67.97.

2. For "Not Colorblind - Hit":

Expected Frequency (Not Colorblind - Hit)=(1808×707)2000=12782562000=639.13\text{Expected Frequency (Not Colorblind - Hit)} = \frac{(1808 \times 707)}{2000} = \frac{1278256}{2000} = 639.13 Rounded to two decimal places, the expected frequency is 639.13.

3. For "Not Colorblind - Miss":

Expected Frequency (Not Colorblind - Miss)=(1808×291)2000=5267282000=263.36\text{Expected Frequency (Not Colorblind - Miss)} = \frac{(1808 \times 291)}{2000} = \frac{526728}{2000} = 263.36 Rounded to two decimal places, the expected frequency is 263.36.

Step 3: Complete the table

Now, we can fill in the table:

Trial OutcomeHitMissFalse AlarmCorrect RejectionTotal
Colorblind77222367.97192
Not Colorblind639.13263.362716381808
Total7072912947082000

The blanks have been filled with the expected frequencies rounded to two decimal places.

Would you like any further clarifications or details?


Here are 5 related questions to explore this topic further:

  1. How do you interpret expected frequencies in a contingency table?
  2. What is the chi-square test for independence, and how is it related to this problem?
  3. How would you calculate the chi-square statistic based on observed and expected frequencies?
  4. What are the conditions for using a chi-square test on categorical data?
  5. How does the concept of statistical independence apply in the context of contingency tables?

Tip: When using contingency tables, always check if the row totals, column totals, and grand total match the original data to ensure accuracy in your calculations!

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Math Problem Analysis

Mathematical Concepts

Probability
Contingency Tables
Expected Frequencies
Statistical Independence

Formulas

Expected Frequency = (Row Total * Column Total) / Grand Total

Theorems

Chi-Square Test of Independence

Suitable Grade Level

College-level Statistics