ENVM 510 Environmental Health and Epidemiology Fall 2016 Week 5 Graded Assignmen
ID: 802543 • Letter: E
Question
ENVM 510
Environmental Health and Epidemiology
Fall 2016
Week 5
Graded Assignment
Instructions:
The use of statistics in epidemiology to helps determine differences in risk due to exposures and allows for the evaluation of associations with respect to validity in order to strengthen study conclusions. Imagine that you are an epidemiologist investigating the development of leukemia associated with occupational exposures to benzene. Employment records identify a total of 9,024 individuals who have worked in a facility where benzene is present. Of the 9,024 individuals, you are able to locate 3,249 individuals. Of those persons located, 487 have leukemia.
Your investigative team also decides to conduct an occupational surveillance program at a facility to identify those who are subjected to excessive benzene exposures. You screen a total of 1,832 workers using a new diagnostic test, and 214 workers with excessive benzene exposure test positive. A negative test finding was observed in 29 workers who had excessive exposure to benzene, and 90 workers without excessive benzene exposure tested positive.
1. Identify potential sources of bias in this study.
2. Describe how these potential sources of bias could be addressed in future studies.
3. Based on the results of the screening test, construct a 2 x 2 table and calculate the following measures:
Sensitivity
Specificity
Prevalence of excessive benzene exposure
Positive predictive value
Negative predictive value
Accuracy
4. Based on the results of the screening program, what conclusions would you draw regarding the new diagnostic test?
Please make sure that you answer each part of the question and that you do so using complete sentences, proper spelling and grammar, etc. Make sure your answers are thorough, yet concise and that you support your responses with at least two (2) appropriately cited references. Wikipedia is not an acceptable reference. Submission Instructions:Assignments must be submitted in Word file as Lastname_ENVM510_M5GradedAssign by 11:55pm EST on Friday, September 3 2016
Explanation / Answer
answer- the new diagnostic test in which 214 workers find excessive benezene out of 1832 workers. biases is realted here availability of workers to study benzene exposures. exposure opportunity, recall of leukemia desease and cofounding. In the aobve test we have compared the workers who have pistive exposures of excessive benzene and who have negative exposures of benene. and second bias is there detection of leukemia disease in workers who have positive excessive benezene exposures.
answer- these above biases will be help in conducting such diagnostics test and when we have to detect the some disease on the based symptoms or identify the those peoples who have positive exposures. These also helps in refering the systematic difference between characterstics of group of individual that are compared . It will also allow allocting the intervention to participants. By such biases care is provided group who have positive exposures.
answer-
sensitivity - number of disease positive testing positive/ number of disease positive testing positive+number of disease positive testing negative
= 214/214+29 = 0.88
specificity- number of disease positive testing negative/ number of disease positive testing positive+number of disease positive testing negative
= 29/214+29 = 0.12
prevalance of excessive benzene exposures 243
positive predictive value 214
Negative predictive value 90
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