Chapter 9 and 11 (from in class packet)

Question 0

is disease deterministic?

Answer 0

yes

Question 1

does human disease come at random?

Answer 1

no it does NOT come at random

Question 2

is association a cause and effect?

Answer 2

no

Question 3

what is the statistical dependence between two variables

Answer 3

association

Question 4

what are the questions that is used to assess validity of association?

Answer 4

• does the observed association really exist?
• is the association valid?
• are there alternative explanations for the association?

Question 5

What are the alternative explanations for the association?

Answer 5

• chance
• bias
• confounding

Question 6

What is the null hypothesis?

Answer 6

• we prove that something ISN’T

- there is NO ASSOCIATION

Question 7

what is the alternative hypothesis?

Answer 7

there IS an association between exposure and disease beyond random error or chance

Question 8

Explain one-sided.

Answer 8

association is greater than expected OR association is less than expected

CAN’T BE BOTH

Question 9

What is two-sided?

Answer 9

there is an association between than those who have greater expectancy or lesser expectancy

Question 10

What are the three Guidelines for Developing Hypotheses?

Answer 10

• state the EXPOSURE to be measured as specifically as possible
• state the health OUTCOME as specifically as possible
• strive to explain the smallest amount of ignorance

Question 11

What are the 2 types of cohort studies?

Answer 11

• prospective

- retrospective

Question 12

What are the 5 steps of cohort studies?

Answer 12

1. select 2 groups (exposed and nonexposed)
2. follow them
3. determine the INCIDENCE of disease in both groups
4. compare RATES among the exposed to rates in the non-exposed
5. interpret the data

Question 13

What is the risk in the exposed qual to the risk in the non exposed (no association)

Answer 13

RR=1

Question 14

What is the risk in the exposed is GREATER than the risk in the non-exposed (positive association)

Answer 14

RR>1

Question 15

What is the risk in the exposed is LESS than the risk in the non-exposed (negative association) protective effect?

Answer 15

RR<1

Question 16

What is the equation of relative risk?

Answer 16

risk in exposed/ risk in nonexposed

Question 17

For relative risk >1 what is the equation?

Answer 17

(RR-1) x 100= the % increase change

Question 18

for relative risk <1 what is the equation?

Answer 18

(1-RR) x 100= the % decrease in change

Question 19

what are ADVANTAGES of cohort study?

Answer 19

• multiple outcomes can be measured for any one exposure
• can look at multiple exposures
• exposure is measured before the onset of disease; less potential for recall bias
• good for rare exposures
• temporal relationship between exposure and disease
• allows examination of natural course of disease, survival

Question 20

What are Disadvantages for cohort disease?

Answer 20

• costly and time consuming
• need large sample size
• loss to follow-up (subjects movem, die, no longer interested)> bias
• participants may move between one exposure category
• knowledge of exposure status may bias classification of the outcome
• being in the study may alter participant’s behavior
• poor choice for the study of a rare disease
• classification of individuals (exposure or outcome status) can be affected by changes in diagnostic procedures