A study is done to investigate a certain suspected diseaseca

A study is done to investigate a certain suspected disease-causing agent. One thousand people are chose at random from the population and each is classified as to 1.) diseased or not diseased, and 2.) exposed to the agent or not exposed. The results could be exhibited in the following table

Exposure

yes no

Disease yes

no

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Use EY (exposure yes) and EN (exposure no); and DY(disease yes) and DN (disease no). Express each of the following statements in terms of conditional probabilities. (MAJORITY MEANS MORE THAN HALF)

A.) The disease is more common among exposed than among nonexposed people

B.) Exposure is more common among diseased people that is non-exposure

C.) A majority of exposed people are diseased

D.) Exposed people are more likely to be diseased than are nonexposed people.

E.) What is the null hypothesis for a row orientation context?

Solution

a)The disease is more common among exposed than among non-exposed people=P(DY|EY) >P(DY|EN)

b)Exposure is more common among diseased people that is non-exposure=P(EY|DY)>P(EN|DY)

c)A majority of exposed people are diseased=P(DY|EY) >1/2

d)Exposed people are more likely to be diseased than are nonexposed people=P(EY|DY) >P(EN|DY)

e)the null hypothesis for a row orientation context

H₀₁: exposure has no effect on disease ag H1₁:Not H₀₁

H₀₂: disease has no effect on exposure ag H₁₂:Not H₀₂