Negative Predictive Value

by | Apr 25, 2023 | Analysis

Instructions: Please show all calculations. Your submission should be in a single PDF file.
1. In an epidemic, an exposure source can be described as common exposure, point exposure, propagated exposure, or mixed exposure.
a. Which source of exposure is described by the epidemic curve below, and why? (4pts)

b. Give an example of the exposure source in the figure above. (2Pts)
c. Outline four (4) useful information that can be derived from epidemic
curves. (4Pts)
2. Consider the epidemic curve from an outbreak of Ebola (below). If the average incubation period for Ebola is 9 days (minimum of 2 days and
maximum of 21 days), determine the most likely period of exposure. (10Pts)

Ebola Cases by Date of Onset, Spring City, November 2015
3. Discuss, with examples, the following terms as applied to screening tests: (10Pts)
● Sensitivity
● Specificity
● Positive Predictive Value
● Negative Predictive Value
4. Tonometer, a screening test for glaucoma, measures intraocular pressure. Some people with glaucoma have intraocular pressures as low as 22 millimeters of mercury (mm Hg), while other people can have intraocular pressures as high as 27 mm Hg. Discuss the effect on sensitivity, specificity, false positive rate, and false negative rate, if ……
● Diagnostic cut-point is set at 22 millimeters of mercury. (4Pts)
● Diagnostic cut-point is set at 27 millimeters of mercury. (4Pts)
● What should be the preferred diagnostic cut point, and why? (2Pts)
5. Compare and contrast the following study designs in epidemiological methodology. (10Pts)
● Cross-Sectionaldesign
● Case-Control study design
● Prospective Cohort study design
6. (i) Discuss the importance of age-adjustment in epidemiology. (5Pts) (ii) Distinguish between direct and indirect age-adjustment. (5Pts)
7. (i) Discuss, with examples, four (4) characteristics of diseases appropriate for screening. (4Pts)
(ii) Discuss, with examples, six (6) characteristics of screening tests (4pts) (iii) Discuss the importance of disease prevalence in planning screening programs (2Pts)
8. (i) What is confounding and why is it an important consideration in epidemiological studies? (6Pts)
(ii) Discuss four (4) approaches to control for confounding. (4Pts)
9. Discuss, with examples, the following terms in the Hill’s Criteria for assessing causality. (10Pts)
a. StrengthofAssociation b. Biological Plausibility c. Temporality
d. Biological Gradient
e. Consistency
10.Discuss the relationship between sample size and confidence interval, and their association with precision of epidemiological studies. (10Pts)
11.a. Define Vaccine Efficacy. (2Pts)
b. Calculate and interpret the vaccine efficacy of a new COVID-19

vaccine presented in the table below: (8Pts)

12.The table below presents results of a study investigating tobacco use and risk of hypertension:

Calculate and interpret the following: (10Pts)
● Relative Risk (RR)
● Attributable Risk (AR)
● Attributable Fraction (AR %)
● Population Attributable Risk (PAR %)
13.Hepatitis B virus (HBV) is suspected in many prison inmates. Only one screening test for HBV is available, and it is 88% sensitive, and 76% specific. If 1,000 prison inmates were screened using such a test, and the true prevalence of HBV infection in that population was 25%, calculate and interpret the following: (10Pts)
a. Positive predictive value (PV+) b. Negative predictive value (PV-)
14.In a field study to investigate the effect of Alcohol consumption on hypertension, cases and controls were matched and data collected in pairs as shown in the table below: (10Pts)

Complete the follow table:

● Calculate and interpret the Odds Ratio
● Compute and interpret the 95% Confidence interval
● Is the association between alcohol consumption and hypertension
statistically significant? Explain.
15.Consider a hypothetical study in which an investigator enrolled 2600 subjects to compare subjects who had diabetes in the past year to subjects who have not had diabetes within the past year for history of alcohol consumption. (10Pts)
● What type of study design is the investigator using?
● Assume the following results: 2600 subjects were enrolled in the study. Of
these subjects 220 who had diabetes also had a history of alcohol use. 60 subjects had diabetes but did not have a history of alcohol use. A total of 1080 subjects in the study had no history of alcohol use. Calculate the risk of having diabetes for subjects with a history of alcohol use compared with subjects without a history of alcohol use. [In other words, calculate either the odds ratio or relative risk, whichever is more appropriate, and interpret your result].
● Calculate and interpret the 95% Confidence Interval for the risk estimate calculated above.
● Is the risk estimate calculated above statistically significant? Explain.

 

Sample solution

Dante Alighieri played a critical role in the literature world through his poem Divine Comedy that was written in the 14th century. The poem contains Inferno, Purgatorio, and Paradiso. The Inferno is a description of the nine circles of torment that are found on the earth. It depicts the realms of the people that have gone against the spiritual values and who, instead, have chosen bestial appetite, violence, or fraud and malice. The nine circles of hell are limbo, lust, gluttony, greed and wrath. Others are heresy, violence, fraud, and treachery. The purpose of this paper is to examine the Dante’s Inferno in the perspective of its portrayal of God’s image and the justification of hell. 

In this epic poem, God is portrayed as a super being guilty of multiple weaknesses including being egotistic, unjust, and hypocritical. Dante, in this poem, depicts God as being more human than divine by challenging God’s omnipotence. Additionally, the manner in which Dante describes Hell is in full contradiction to the morals of God as written in the Bible. When god arranges Hell to flatter Himself, He commits egotism, a sin that is common among human beings (Cheney, 2016). The weakness is depicted in Limbo and on the Gate of Hell where, for instance, God sends those who do not worship Him to Hell. This implies that failure to worship Him is a sin.


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God is also depicted as lacking justice in His actions thus removing the godly image. The injustice is portrayed by the manner in which the sodomites and opportunists are treated. The opportunists are subjected to banner chasing in their lives after death followed by being stung by insects and maggots. They are known to having done neither good nor bad during their lifetimes and, therefore, justice could have demanded that they be granted a neutral punishment having lived a neutral life. The sodomites are also punished unfairly by God when Brunetto Lattini is condemned to hell despite being a good leader (Babor, T. F., McGovern, T., & Robaina, K. (2017). While he commited sodomy, God chooses to ignore all the other good deeds that Brunetto did.

Finally, God is also portrayed as being hypocritical in His actions, a sin that further diminishes His godliness and makes Him more human. A case in point is when God condemns the sin of egotism and goes ahead to commit it repeatedly. Proverbs 29:23 states that “arrogance will bring your downfall, but if you are humble, you will be respected.” When Slattery condemns Dante’s human state as being weak, doubtful, and limited, he is proving God’s hypocrisy because He is also human (Verdicchio, 2015). The actions of God in Hell as portrayed by Dante are inconsistent with the Biblical literature. Both Dante and God are prone to making mistakes, something common among human beings thus making God more human.

To wrap it up, Dante portrays God is more human since He commits the same sins that humans commit: egotism, hypocrisy, and injustice. Hell is justified as being a destination for victims of the mistakes committed by God. The Hell is presented as being a totally different place as compared to what is written about it in the Bible. As a result, reading through the text gives an image of God who is prone to the very mistakes common to humans thus ripping Him off His lofty status of divine and, instead, making Him a mere human. Whether or not Dante did it intentionally is subject to debate but one thing is clear in the poem: the misconstrued notion of God is revealed to future generations.

 

References

Babor, T. F., McGovern, T., & Robaina, K. (2017). Dante’s inferno: Seven deadly sins in scientific publishing and how to avoid them. Addiction Science: A Guide for the Perplexed, 267.

Cheney, L. D. G. (2016). Illustrations for Dante’s Inferno: A Comparative Study of Sandro Botticelli, Giovanni Stradano, and Federico Zuccaro. Cultural and Religious Studies, 4(8), 487.

Verdicchio, M. (2015). Irony and Desire in Dante’s” Inferno” 27. Italica, 285-297.

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