Statistics Flashcards
Order of Research Hierarchy
• Systematic Review &
Meta-Analysis
• Randomized Controlled
Trials
- Cohort Study
- Case study
- Expert opinions
What is an Independent Variable?
Independent variable (Intervention)
• A condition, intervention, or
characteristic that will
predict or cause a given outcome.
What is a Dependent Variable?
Dependent variable (outcome)
• The response or the effect
that presumed to vary
depending on the
independent variable
What is a Null Hypothesis?
- Null Hypothesis (Ho)
- Why do we need this
- Establishes a possible explanation for
the results of the experiment
- What is a null hypothesis
- No difference
- Hypothesis conclusion
- If I “Do Not Reject” the null hypothesis,
I am saying there is no difference
• If I “Reject” the null hypothesis,
I am saying that there is a difference
What is Significance Value (Alpha-value)?
We set this at the beginning of our
research.
The risk that we are willing to take that
results are due to chance.
- Example
- α = 0.01 = 1%
- α = 0.02 = 2%
- α = 0.05 = 5%
- α = 0.1 = 10%
What is the Probability Value (P-value)?
the probability of finding a significant
change when there actually isn’t one
present.
“The probability of making a mistake”
- Example
- If we set α = 0.05 = 5% and p < 0.05
- There is a REAL change and we
[reject] the Null Hypothesis
Type 1 error?
• Smooth Criminal
Stating that there is a significant
difference when no true difference
exists
- Why is it important?
- Stating that a certain intervention is
superior for improving balance when it
isn’t can delay delay patient progress
- Example
- Incorrectly rejecting the null
hypothesis
What is the Beta Value?
the probability of stating
that there is no real change
when there actually is a real
change present.
- Example
- B= 0.20 = 20%
What is a Type 2 error?
- Hiding In Plain Sight
- Stating that there is not a real change when
there is a real change
- Why is it important
- Stating that a certain intervention does not
yield a significant difference when it does
- Example
- Failing to reject the null hypothesis
What is Power?
• The probability that
we will be able find a
difference when one
truly exists.
- Example,
- 80% is normal
FACTORS THAT INFLUENCE POWER:
Sample Size
• The larger the sample, the
greater the statistical power.
- Variance
- The power is increased as the
variance within a group is
reduced 1 2 3 4
- Significance Criterion
- The power is increased as the
alpha value is increased Alpha Value set to 0.05, 0.1, or higher
- Effect size
- Amount of significant change
observed
What is a dependent (paired) T test?
- Statistical Test
- Used to determine the difference within the same
person or same group of people
• Pre intervention & Post-intervention
What is an independent (unpaired) T-test?
Statistical Test
• Used to determine the difference between two
independent groups of data
One Tailed versus Two-Tailed T-Test
Dependent on your initial
hypothesis
• If you hypothesize that
that the 8-week
quadriceps program will
have a longer single leg
stance time than the
general exercise group
then you run a one tail ttest.
• If you hypothesize that
that there will be a
difference between the
two groups but you don’t
know if the 8-week
quadriceps program will
have a longer or shorter
single leg stance time than
the general exercise group
then you run a two tail ttest.
What is ANOVA used for?
Statistical procedure appropriate for comparison of three or more treatment groups or conditions
What is a Bell Curve Skew?
