Lexie F.

Aim of descriptive studies?

To describe...

Characteristics

Lifestyle patterns

Attitudes

Method of descriptive studies?

Select a subgroup (sample) from the population of interest

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Random error vs. systemic error

Random error: due to biological variability

Systemic error: due to aspects of design or conduct of the study

Aim of analytic studies?

To describe...

Causes

Methods for prevention

Effectiveness of treatment

Name two types of analytic studies.

Experimental: The researcher intervenes

Observational: The researcher observes a naturally occurring process

What do analytic studies describe?

Causes, methods for prevention, and effectiveness of treatment

What is the methodology of an experimental study?

The researcher intervenes and records the result of their intercention

What is the methodology of an observational study?

The investigator observes a naturally occurring process and records information

What is the methodology of a case control study?

See if someone has a condition, check if they are x or y

What is the difference between an experimental and observational form of design?

Experimental- intervenes

Observational- observes

What is the response vs explanatory variable?

Response- Outcomes measured on each experimental unit; y

Explanatory- Characteristics of levels of exposure that explain at least some of the differences in the observed values of the response variable; x

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Prevalence

Frequency of existing cases of a disease at a given point in time

Incidence

Frequency of new cases of a disease

Observational cohort study

Looks at number of cases that develop

Incidence rate

New cases of disease during the time period / total person-time at risk

Cumulative incidence

Proportion of people who become diseased over a period of time

Cumulative incidence

New cases of disease during time period / total population at risk

Complementary events

All outcomes are either of the two sums

Mutually exclusive events

No intersection between the events

Pr(A or B) = Pr(A) + Pr(B)

The addition rule (not mutually exclusive)

Pr(A or B) = Pr(A) + Pr(B) - Pr (A and B)

Multiplication rule

Pr(A and B) = Pr(A)Pr(B I A)

Sensitivy

True positive rate

Sick people who are actually sick

Pr (A I B)

Specifity

True negative rate

Negatives who are correctly identified as such

Pr(not A I not B)

Random variable

Has values that depend on the outcome of a random experiment

Binomial distribution

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