Experimental Studies Use Blinding to Prevent Researchers from Biasing Their

question 41

Essay

Experimental studies use blinding to prevent researchers from biasing their measurements of the subjects. In a study of a drug intervention, a clinician who was
"blinded" was asked to guess what treatment each subject received. Data from that
experiment are shown below. Suppose a person is to be chosen at random from the
subjects in this study. $$\begin{array}{l}\text { Frequencies for Blinding Experiment }\\\begin{array} { | l | c | c | } \hline & \text { Correct Guess } & \text { Incorrect Guess } \\\hline \text { Drug } & 23 & 12 \\\hline \text { Standard treatment } & 32 & 6 \\\hline\end{array}\end{array}$$ a) What is the probability that the clinician made a correct guess for the selected
subject?
b) What is the probability the selected subject received the drug treatment?
c) What is the probability the selected subject will be one for whom the clinician
correctly guessed as having received drug treatment?
d) What is the probability the selected subject will be one for whom the clinician
guessed correctly or who received the standard treatment?
e) What is the probability the selected subject will be one for whom the clinician
guessed correctly and who received the standard treatment?
f) In a few sentences, explain why the probabilities calculated in parts (d) and (e)
differ.

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Definitions:

Direct Materials Price Variance

The difference between the actual cost of direct materials used in production and the standard cost, multiplied by the actual quantity of materials used.

Direct Labor Rate Variance

The difference between the actual cost of direct labor and the expected (or standard) cost, used in variance analysis to control labor costs.

Direct Materials Cost Variance

The difference between the budgeted cost of materials for products and the actual cost incurred.

Direct Labor Rate Variance

The difference between the actual cost of labor per hour and the standard or expected cost, multiplied by the total labor hours worked.