Introduction to Biostatistics Flashcards
What are 2 key attributes of data measurements?
- magnitude
- consistency of scale (mmHg, cm, lbs)
- rational/absolute zero. (but does not have an effect of what test to use for analyzing data)
What are the three categories, that test data can be organized into based on ‘yes’/’no’ of 2 important key attributes?
- nominal
- ordinal
- interval/ratio
What components would direct the use of a nominal categorization?
- no magnitude, therefore no scale consistency, and no rational zero.
- labeled variables with no quantitative quality.
- can arrange heights into specific category of being taller or shorter than 50in.
What is meant if a null hypothesis possesses superiority?
- the collected data suggests the testing object will work better than its comparative.
What is meant if a product is deemed equivalent?
-it does not show proof of working better than the comparator, but works just as good as.
What does noninferiority mean?
-it is the new up and coming way to describe products that can be categorized as being either equivalent to or better than the comparator. Data not available to indicate superiority or equivalency, but it is not worse than the comparator.
What assumptions must be made for interval tests?
assume:
- normal distribution
- equal variances which can be tested with the Levene’s Test
- data is randomly derived and independent
If the interval data is not able to be normally distributed what two way allow for the analysis of the data?
- use of non-parametric test
- use a z score or a log test in order to transform that data to become normally-distributed
Type I error?
the ability to find the difference if one truly exists
Type II error?
claims no difference is present when in reality a difference is truly present
What is Power?
- (1 minus Beta)
-the ability of the study test to detect a true difference when one truly exists.
Explains the level of accuracy of accepting or rejecting the Null Hypothesis
How can you minimize the difference between groups that are deemed significant?
-increase the number of study subjects. Thereby reducing the difference between groups
If the p-value is lower than the pre selected value what course of action is soon to follow after?
- there is a statistical difference somewhere
- another test is performed to evaluate where the difference is
- the lower (closer to 0) the less chance of a type I error
What are confidence intervals?
-pre calculated values that display where the true relationship exists in a high and low range of data.
What are the confidence intervals based on?
- variation in sample
- sample size
What can you conclude of a ratio (ORR,RR,HR) that crosses the value 1.0?
- nothing significant can be concluded as this suggests that x amount benefit and y amount are hindered.
What can you conclude for comparison data that is not a ratio, that crosses over the value 0.0?
- nothing significant can be concluded as this suggests that x amount benefit and y amount are hindered.
What question must we always ask when reviewing the findings of a study?
- does the statistical data represent significance in the clinical setting?
What does a correlation test represent?
-provides a quantitative measure of strength and direction between variables betweem -1.0 to 1.0
What does a partial correlation test able to control?
- controls for confounding
The contingency coefficient is used when?
-nominal correlation test
Spearman correlation is used for ________
-ordinal correlation test
Pearson correlation test is used for ________
- interval correlation test
- no linear correlation if the p>0.05, but a non-linear correlation can exist.
The tip and hint for a survival test is what word?
time
How are survival tests best represented?
- Kaplan Meier graph which compares the proportion of event occurrences between groups
The log-rank test is used for ______
a nominal survival test
The Ordinal survival test is what?
cox-proportional hazards test
What test is used for interval survival test?
Kaplan- Meier test
Name a nominal regression test.
- Logistic regression
- tipped off by “prediction”