STAT (4th Quarter) Flashcards
is a type of observational
study design. In this study, the
investigator measures the
outcome and the exposures
in the study participants at
the same time. (compared at the same time)
Cross-sectional study design
researchers repeatedly
examine the same individuals
to detect any changes that
might occur over a period of
time. (Compared over the time)
longitudinal study,
Types of Longtidunal Study
Panel Study
Cohort study
Retrospective study
involves a sample of people from a more significant population
and is conducted at specified intervals for a more extended period.
panel survey
Its essential features is that researchers collect data
from the same sample at different points in time.
panel study’s
are designed for quantitative analysis, though they may also be used to collect qualitative data and analysis.
panel studies
researchers use __________ to accurately measure
specific parameters and human behaviors
panel surveys
samples a cohort (a group of people who typically
experience the same event at a given point in time). Medical
researchers tend to conduct cohort studies. Some might consider
clinical trials similar to cohort studies.
cohort study
researchers merely observe participants without
intervention, unlike clinical trials in which participants undergo
tests.
cohort studies,
They are planned in advance and carried out in a future period of
time. In this study, individuals do not have the disease, but it is
observed over a period of time to observe the frequency of its
manifestation in different groups.
Prospective study
uses already existing data, collected during previously
conducted research with similar methodology and variables.
retrospective study
Possible sources of biases in a sample surveys
that one should be cautious about:
- Wording of questions
- Sensitivity of the survey topic
- Interviewer biases
- Non-response biases
which can influence the response enormously
Wording of questions
income, sex, illegal behavior, etc.
Sensitivity of the survey topic
in selecting respondents or in the responses generated because of the
appearance and demeanor of the interviewer.
Interviewer biases
which happens when targeted respondents opt not to provide information
in the survey
Non-response biases
Type of survey errors
Sampling Error
Non-Sampling Error
It results from chance variation from sample to sample in a probability sample.
It is roughly the difference between the value obtained in a sample statistic and
the value of the population parameter that would have arisen had a census
been conducted.
Sampling Error
Types of Non-Sampling Error
Coverage error or selection bias
Non-response error or bias occurs
Measurement error
results if some groups are excluded from
the frame and have no chance of being selected.
*Coverage error or selection bias
occurs when people who do not respond may
be different from those who do respond.
- Non-response error or bias occurs
It is how likely something is to happen. “chance”
Probability
- A context wherein possible outcomes are well defined and can
be specified, at least in principle, beforehand.
Random Process
We do not know which of the possible outcomes will occur,
but we do know what is on the list of possible outcomes.
Random Process
It is a way to map outcomes of a statistical experiment
determined by chance into number
Random Variable
is an activity that will produce
outcomes, or a process that will generate data. The outcomes
have a corresponding chance of occurrence.
Statistical Experiment
are random variables that can take
on a finite number of distinct values.
Discrete Random Variables
are random variables that take
an infinitely uncountable number of possible values, typically measurable
quantities.
Continuous Random Variables
The collection of information from a sample of individuals through
their responses to questions.
Survey
is a method of systematically gathering
information on a segment of the population such as individuals,
families, wildlife, farms, business firms, and unions of workers,
for the purpose of quantitative descriptors of the attributes of
the population.
A sample survey
A sample often provides useful and reliable information at a much lower
cost than a census.
Cost
A sample usually provides more timely information because fewer data
are to be collected and processed. This attribute is particularly important
when information is needed quickly.
Timeliness
A sample often provides information as accurate, or more accurate, than a
census, because data errors typically can be controlled better in smaller
tasks.
Accuracy
More time is spent in getting detailed information with sample surveys
than with censuses.
Detailed information
When a test involves the destruction of an item, sampling must be used.
Destructive testing
involves random selection, allowing you
to make strong statistical inferences about the whole group
Probability sampling
involves non-random selection
based on convenience or other criteria, allowing you to easily
collect data.
Non-probability sampling
is a type of
probability sampling in which the
researcher randomly selects a subset of
participants from a population. Each
member of the population has an equal
chance of being selected. Data is then
collected from as large a percentage as
possible of this random subset.
Simple random sampling
the population is
divided into two or more strata
based on common characteristics.
Stratified sampling
It is an extension of simple random
sampling which allows for different
homogeneous groups,
strata,
Elements are selected from
the population at a uniform
interval that is measured in
time, order, or space. There
is firstly, a decision on a
desired sample size.
Systematic sampling
It is a probability sampling
method in which you divide a
population into clusters, such
as districts or schools, and then
randomly select some of these
clusters as your sample.
Cluster Sampling
It is a type of nonprobability sampling in which people are
sampled simply because they are “convenient” sources of data
for researchers. Under this method, researcher does not take
special efforts to select the sample, but simply selects those who
are immediately available
Haphazard or accidental sampling
, participant volunteer rather than being
chosen.
volunteer sampling
pertains to having an expert select a
representative sample based on his own subjective judgment.
Purposive sampling
sample
units are picked for
convenience but certain
quotas (such as the number
of persons to interview) are
given to interviewers. This
design is especially used in
market research.
Quota Sampling,
is a statistical term that describes a division of observations into four defined intervals based on the values of the data and how they compare to the entire set of observations.
quartile
is a term used in statistics to express how a score compares to other scores in the same set.
percentile
indicates the percentage of scores in the distribution that falls less than or equal to that score.
percentile rank
is equal to the median.
The second quartile
