Explanatory Research Flashcards
Therapeutic clinical trials examine:
the effect of the variable
preventative clinical trials examine:
capability variable (procedure/agent) to reduce the risk of developing a disease
How is the design of the explanatory created?
off of the degree of experimental control (true experimental design or quasi experimental)
how subjects are assigned into groups (between-subjects design vs. within-subject design)
What is the difference between true experimental and quasi-experimental?
quasi-experimental lacks random assignment.
Describe characteristics of between-subjects designs.
- subjects randomly assigned into different groups.
- each group is exposed to a different independent variable.
- SFD - 1 independent variable
MFD - 2 or more independent variables
describe characterstics of within subject designs.
- subjects act as their own baseline
- all subjects are exposed to all of the independent variables.
What are pros of between subject - designs?
shorter duration of study and prevents carry over effects
what are cons of between subject groups?
requires larger sample sizes and validity risk from differing individual characteristics
What are the pros of within-subject groups?
can use smaller sample size and removes effects of individual effects on conditions (increases statistical power)
what are cons of within-subject groups?
takes longer to collect data
concern for carryover effects (practice, order, sequence)
What are the 2 between subjects group designs?
pretest-posttest control group designs and post-test only control group design.
what are the independent variables called in a pretest-posttest design called?
treatement arms.
When is the posttest only control group design utilized?
when pretesting is not feasible or safe.
A one way repeated measure design is a single or multi - factor experiment where one group of subjects is:
exposed to 1 or more independent variables.
With the one-way repeated measure design, what are we concerned for and what is the solution?
concern: order effect
solution: counterbalancing: washout period between conditions.
what 2 designs does a within subjects test utilize?
one way RM design and crossover design
which design is the preferred method for controlling order effects when 2 independent variables are involved?
crossover design
crossover designs can only be utilized when the subject conditions remain:
stable.
Crossover designs are not reasonable when:
treatment effects are permanent or slow
What 5 questions should we ask to determine what study is best?
- How many independent variables are being tested?
- How many levels does each independent variable have and are these levels experimental or control conditions?
- How will subjects be assigned to groups?
- How often will observations of responses be made?
- What is the temporal sequence of interventions and measurements?
Inferential statistics allow us to:
estimate population parameters and compare between groups.
What is the purpose of the sampling error?
It tells us that our sample will never be a perfect representation of the population.
The sampling distribution of means is a _____________ concept.
theoretical
The sampling distribution of means states that all possible sample means within a population create:
a normal distribution curve to help determine variability.
The central limit theorem states that the sampling distribution of sample means will approach a normal distribution and as the sample size gets larger, the ___________________ will decrease.
Standard Error of Means (SEM)
Does the central limit theorem depend on the shape of the original population distribution?
NO
What is the standard error of mean?
the estimate of the population standard deviation
If the SEM is higher, does this mean there is more or less variability in the sample?
MORE
If the SEM is higher, is this more or less representative of the population?
LESS
As sample size increase, what happens to SEM?
it decreases
What two values do you use to calculate SEM?
The sample total and standard deviation
Confidence interval =
1 - alpha
what is alpha?
the significance level/accepted error
What does the confidence interval do?
provides an estimated range of values which is likely to include an unknown population parameter, the estimated range being calculated from a given set of sample data.
What does the confidence interval do?
provides an estimated range of values which is likely to include an unknown population parameter, the estimated range being calculated from a given set of sample data.
What do you use to calculate the CI?
sample mean and standard deviation
What is probability used for in research?
as a guideline for how well sample represents the population.
probability, or p, =
likelihood event will occur/ all possible outcomes.
If P is 0, this means
no chance event will occur
If P = 1, this means
100% chance event will occur.
What are the common objectives of interferential statistics?
estimate population parameters with confidence intervals
and
compare between groups with confidence intervals and statistical hypothesis testing
The p value quantifies how __________ sample values are with the null hypothesis
consistent
p value is calculated from the deviation between:
the observed value and a chosen reference value
What is a type 1 error in hypothesis testing?
conclusion that a difference exists when there is not one
what is a type 2 error in hypothesis testing?
conclusion that a difference does not exist when in fact, there is one.
