1.3 observational studies Flashcards

1
Q

experimental units

A

individuals who are studied (i.e. people, animals, plants, plots of land or things) people are sometimes called subjects

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2
Q

treatment

A

procedures applied to each experimental unit (i.e. type of seed, formaldehyde level)

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3
Q

outcome/response

A

what is measured on each experimental unit (i.e. amount of growth, degree of respiratory problems)

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4
Q

randomized experiment

A

study in which the investigator assigns treatments to the experimental units at random

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5
Q

observational study

A

one in which the assignment to treatment groups is not made by the investigator

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6
Q

why randomize?

A

in reality, treatment groups differ from each other no matter how much they are alike.
randomization makes small differences only due to chance
large differences in outcomes among groups can be concluded that the differences are due to the treatments

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7
Q

why observational studies are less reliable AKA confounding?

A

it’s hard to tell whether a difference in the outcome is due to the treatment or to some other difference between the treatment and control groups. AKA confounding

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8
Q

what are the two types of observational studies?

A

cohort and case-control

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9
Q

what are the types of cohort studies?

A

prospective, cross-sectional, retrospective

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10
Q

cohort study

A

group of subjects is studied to determine whether carious factors of interest are associated with an outcome

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11
Q

prospective cohort study

A

where the subjects are followed over time

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12
Q

cross-sectional

A

where measurements are taken at one point in time (i.e. when the respiratory problems were measured on one point a time in a single day)

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13
Q

retrospective cohort study

A

subjects are sampled after the outcome has occurred

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14
Q

case-control study

A

two samples are drawn. there are the cases and the controls. the investigators look back in time to determine whether a factor of interest differs between the two groups

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15
Q

the cases

A

the people of have the disease of interest

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16
Q

the controls

A

the people who do not have the disease

17
Q

explanatory variable

A

the independent variable/ the variable causing the outcome

18
Q

response variable

A

dependent variable/ the outcome being studied