A diagnostic test for a certain disease is applied to n individuals known to not have the disease. Let X = the number among the n test results that are positive (indicating presence of the disease, so X is the number of false positives) and p = the probability that a disease-free individual's test result is positive (i.e., p is the true proportion of test results from disease-free individuals that are positive). Assume that only X is available rather than the actual sequence of test results. (a) Derive the maximum likelihood estimator of p. p= If n = 20 and x = 7, what is the estimate? p= (b) Is the estimator of part (a) unbiased? Yes No (c) If n = 20 and x = 7, what is the mle of the probability (1 - p)5 that none of the next five tests done on disease-free individuals are positive? (Round your answer to four decimal places.)

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### Understanding Maximum Likelihood Estimation in Diagnostic Tests

A diagnostic test for a certain disease is applied to \( n \) individuals known to not have the disease. Let \( X \) be the number among the \( n \) test results that are positive (indicating the presence of the disease, so \( X \) is the number of false positives) and \( p \) be the probability that a disease-free individual’s test result is positive (i.e., \( p \) is the true proportion of test results from disease-free individuals that are positive). Assume that only \( X \) is available rather than the actual sequence of test results.

#### (a) Derive the Maximum Likelihood Estimator of \( p \).
\[ \hat{p} = \]

#### If \( n = 20 \) and \( x = 7 \), what is the estimate?
\[ \hat{p} = \]

#### (b) Is the estimator of part (a) unbiased?
- [ ] Yes
- [ ] No

#### (c) If \( n = 20 \) and \( x = 7 \), what is the MLE of the probability \( (1 - p)^5 \) that none of the next five tests done on disease-free individuals are positive? (Round your answer to four decimal places.)
\[ (1 - \hat{p})^5 = \]

### Explanation of Concepts

**1. Maximum Likelihood Estimation (MLE):**
   - The Maximum Likelihood Estimation (MLE) is a method used to estimate the parameters of a statistical model. The MLE is founded on finding the parameter values that maximize the likelihood that the process described by the model produced the data that were actually observed.

**2. False Positives:**
   - In the context of the diagnostic test, a false positive occurs when the test incorrectly indicates the presence of the disease in an individual who does not have the disease.

**3. Unbiased Estimator:**
   - An unbiased estimator is a statistic used to estimate a parameter that, on average, equals the true parameter value. 

**4. Probability of No Positive Results in Future Tests:**
   - This part involves calculating the likelihood that none of the next five tests will return a positive result, given the estimated probability of a single test being positive.

This exercise demonstrates how statistical methods can be applied to interpret and analyze the accuracy and reliability of diagnostic tests.
Transcribed Image Text:### Understanding Maximum Likelihood Estimation in Diagnostic Tests A diagnostic test for a certain disease is applied to \( n \) individuals known to not have the disease. Let \( X \) be the number among the \( n \) test results that are positive (indicating the presence of the disease, so \( X \) is the number of false positives) and \( p \) be the probability that a disease-free individual’s test result is positive (i.e., \( p \) is the true proportion of test results from disease-free individuals that are positive). Assume that only \( X \) is available rather than the actual sequence of test results. #### (a) Derive the Maximum Likelihood Estimator of \( p \). \[ \hat{p} = \] #### If \( n = 20 \) and \( x = 7 \), what is the estimate? \[ \hat{p} = \] #### (b) Is the estimator of part (a) unbiased? - [ ] Yes - [ ] No #### (c) If \( n = 20 \) and \( x = 7 \), what is the MLE of the probability \( (1 - p)^5 \) that none of the next five tests done on disease-free individuals are positive? (Round your answer to four decimal places.) \[ (1 - \hat{p})^5 = \] ### Explanation of Concepts **1. Maximum Likelihood Estimation (MLE):** - The Maximum Likelihood Estimation (MLE) is a method used to estimate the parameters of a statistical model. The MLE is founded on finding the parameter values that maximize the likelihood that the process described by the model produced the data that were actually observed. **2. False Positives:** - In the context of the diagnostic test, a false positive occurs when the test incorrectly indicates the presence of the disease in an individual who does not have the disease. **3. Unbiased Estimator:** - An unbiased estimator is a statistic used to estimate a parameter that, on average, equals the true parameter value. **4. Probability of No Positive Results in Future Tests:** - This part involves calculating the likelihood that none of the next five tests will return a positive result, given the estimated probability of a single test being positive. This exercise demonstrates how statistical methods can be applied to interpret and analyze the accuracy and reliability of diagnostic tests.
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