Author Question: A lab scientist is attempting to develop a screening tool that will detect leukemia before children ... (Read 57 times)

rayancarla1 · **on:** Jul 8, 2018

A lab scientist is attempting to develop a screening tool that will detect leukemia before children show any symptoms of the disease, because it is most curable in its early stages.

The scientist wants a test that will detect all children, whether or not it produces some false positives. What does the researcher want in terms of that new screening tool? (Select all that apply.)
a. Maximum specificity
b. A high LR
c. Maximum sensitivity
d. A high LR+
e. High interrater reliability

Question 2

Which of the statements is true relative to systematic error? (Select all that apply.)

a. If the amount of the systematic error is known, true scores can be retrieved.
b. Systematic error may be decreased by proper instrument calibration.
c. Systematic error results in values that vary in one direction from the true scores.
d. Systematic error results from researcher fatigue or inattention.
e. Systematic error changes the mean but not the relative magnitude of the variance.

Jsherida · **Reply #1 on:** Jul 8, 2018

Answer to Question 1

ANS: A, D
Sensitivity is the ability of a test or diagnostic tool to detect patients with the disease. This is referred to as a true positive. Specificity is the ability of a test or diagnostic tool to detect patients without the disease. This is referred to as a true negative. A test with high sensitivity is very good at identifying the diseased patient. A high positive Likelihood Ratio makes a positive diagnosis almost certain. A high negative Likelihood Ratio makes a negative diagnosis almost certain.

Answer to Question 2

ANS: A, B, C, E
Observed score = true score + systematic error. Measurement error that is not random is referred to as systematic error. For example, a scale that weighed subjects three pounds more than their true weights demonstrates systematic error. All of the body weights would be higher, and, as a result, the mean would be higher than it should be. Systematic error results in error in one direction. Consequently, the mean is either higher or lower, but the relative magnitude of the variance should remain the same. Systematic error occurs because something else is being measured in addition to the concept.