Applied Biostatistics Problem Solving Assignment

PUH 5302, Applied Biostatistics
Unit III Problem Solving Assignment
This assignment will allow you to demonstrate the following objectives:
 4.1 Compute and interpret probability for biostatistical analysis.
 4.2 Draw conclusions about public health problems based on biostatistical methods.
Instructions: In this assignment, you will be applying the concepts of probability that you have learned in
this unit. To complete this assignment, answer the questions directly on this document. You may use as
much space as you need to answer the questions. When you are finished, select “Save As,” and save the
document using this format: Student ID_Unit# (ex. 1234567_UnitI). Upload this document to Blackboard
as a .doc, docx, or .rtf file.
1. Calculate the sample size of an unknown population with the given information. Use the appropriate
formula discussed in the unit lesson. Show your work.
a. 90 % z-score = 1.645
b. Margin of error = (+/- 5%)
c. Standard deviation .5
d. 90% confidence level
Sample size is given as n=( zσ
E )
2
Where z=¿the z-value of the standard normal distribution, at 90% confidence level = 1.645
σ =¿ the standard deviation = 0.5
E=¿margin of error = 5% = 0.05
Thus, n=( 1.645∗0.5
0.05 )
2
= ( 16.45 )2 =270.603
Thus, sample size of the unknown population = 271.
2. Examine the following table carefully:
Screening Disease No Disease Total
Positive A = 10 B = 20 A + B = 30
Negative C = 2 D = 30 C + D = 32
Total A + C = 12 B + D = 50 N = 62
Calculate the following variables by using the appropriate formulas given in the unit lesson.
a. Prevalence
Prevalence ¿ Number of Persons with Disease
Total number of persons examined =10
62 =0.161
b. Sensitivity
P(Positive | Disease) ¿ A
A +C = 10
12 =0.833
c. Specificity