Lesson 1-10 Flashcards
Defining who or what is going to be studied means defining the
population
is a smaller set or a subset of the population
sample
occurs when certain members of the population are chosen so that the sample systematically misrepresents the population
biased sample
must be created where respondents are
listed and assigned a unique number.
sampling frame
Each subject in the population has the same chance of being selected
Simple random sampling
The sampling frame is divided into subgroups or strata and simple random samples are
conducted within the strata.
Stratified random sampling
The sampling frame is ordered, and a number s is selected so that every sth subject is
selected to be in the sample.
Systematic random sampling
is how information on the subjects will be collected.
Study Designs
Subjects are identified and followed for a specific period of time.
Prospective study
a type of medical research used to investigate the causes of disease and to establish links between risk factors and health outcomes.
Cohort study
An outcome is identified, after the data have already been collected.
Retrospective study
Study where previously collected
data are reviewed to determine whether any characteristics impacted the outcome.
Retrospective study
Study where Existing data are then obtained to determine what factors were
related to subjects becoming either a case or a control.
Case control study
those having the outcome
Case subjects
those not having the
outcome
control subjects
Data are collected at a particular time point and represent a cross-section of time.
Cross-sectional study
Variables whose measurements represent a limited set of possible values.
discrete variables
values can be expressed in either?
Numbers, characters, words
These are variables with different levels or categories whose order matters. Examples
include pain scores, stages of cancer, and educational attainment
Ordinal
These are categorical variables with different levels or categories whose order does
not matter. Examples are tooth color, marital status, and political affiliation.
Nominal
These are variables that can have only two levels.
Dichotomous
True or false: Sex is an example of Dichotomous variable
True
Variables whose measurements represent an unlimited set of possible values.
Continuous
These variables can take on only positive, whole number values.
Count
True or false: Continuous variables can have only numeric values.
True
The total number of subjects with a particular category or level
Counts
is simply the count for a category divided by the total number of subjects.
Proportions
is the proportion times 100
Percentages
It provides a description of the average response
measure of center
It provides a description of how varied the responses are
measure of spread
This is commonly used to describe the center of the responses.
Mean
True or false:
when extremely large or small values are present, the mean is a better measure of the center.
False, median is a better measure
These are numerical summaries that describe the sample.
Parameters
are the numerical
summaries that an investigator wants but cannot obtain directly because collecting data on the
entire population is not feasible.
Parameters
These are numerical summaries that describe the sample.
Statistics
What are the the basic sciences of public health.
Epidemiology and biostatistics
is about the understanding of disease development and the methods used to uncover the etiology, progression, and treatment of the disease.
Epidemiology
is collected to investigate a question
Information (data)
variable consists of a summary of the possible values the variable can have and the number of subjects with each of
these values.
distribution
distribution that uses counts to describe the number of subjects with a particular
value
frequency distribution
distribution that uses proportions to describe the
number of the subjects with a particular value
probability distribution
Two types of graphs are used to summarize categorical variables
pie charts and bar graphs.
can be presented using frequencies or proportions
Pie charts
describes how the pieces relate to the whole
Pie charts
They demonstrate how the categories within a variable relate to each other
Pie charts
are used to describe the
distributions of categorical variables.
Bar graphs
are used when a data has a variable with two options.
Binomial distributions
Binomial distributions are what type of variables
dichotomous
best describe the distribution of a continuous variable
Histograms
is a graphical representation of a variable in which the observed values are categorized, a bar is drawn for each category, and the number of participants in each category is represented by the height of the bar.
Histograms
It provides a quick picture of the distribution of a variable and it can be presented with counts or
proportions of participants.
Histograms
They provide information about how spread out the
responses are, which responses are common, which responses are in the center, and the overall
shape of the distribution.
Histograms
can be folded in half so that each half is close to a mirror image of the other
Symmetric distributions
This distribution has one mode or one most common value
unimodal