Biostatistics Flashcards
what is the interquartile range (IQR)?
-middle 50% . . from 25th-75th percentile
what is within 1 standard deviation?
2?
3?
middle 68%
- 95%
- 99.7%
there is a positive skew if what?
negative?
mean>median
mean
What test is used to assess for equal variances between groups in interval data?
Levene’s test
if interval data is not normally distributed then what?
use an ordinal test then
what are the types of comparison/assessment that can be used?
- Correlation
- Regression (predicts an outcome)
- Survival comparison (as time progresses . . something over time)
- Group Comparison
what comparison provides a quantitative measure of the strength and direction of a relationship b/t variables
-values range from -1.0 to +1.0
Correlation
Nominal correlation test?
Contingency coefficient
Ordinal correlation test
Spearman correlation
Interval correlation test
Pearson correlation
what does a Kaplan meier Curve represent?
proportion of events over time . . so a survival comparison
Nominal Survival test?
Log Rank test
Ordinal Survival Test?
Cox-Proportional Hazards test
Interval Survival Test?
Kaplan Meier test
Nominal Regression test?
Logistic Regression
Ordinal Regression test
Multinomial logistic regression
Interval Regression test?
Linear Regression
Nominal Group comparison, 2 groups, independent data
(Pearson’s) Chi-squared or Fisher’s Exact
Nominal Group comparison, 2 groups, related data?
McNemar
Nominal Group comparison, 3 or more groups, independent data
Chi-squared or Fisher’s exact
Nominal Group comparison, 3 or more groups, related data
cochran
What is the Bonferroni test of inequality used for
when a nominal group comparison with 3 or more groups are compared and it is found that there is a difference
Ordinal Group comparison, 2 groups, independent data
Mann-Whitney
Ordinal Group comparison, 2 groups, related data
Wilcoxon Signed Rank
Ordinal Group comparison, 3 or more groups, independent data
Kruskal-Wallis
Ordinal Group comparison, 3 or more groups, Related data
Friedman
When is a Student-Newman-Keul, Dunnet, or Dunn test used
when an ordinal group comparison with 3 or more groups is done and there is a difference
Interval Group comparison, 2 groups, independent data
Student T test
Interval Group comparison, 2 groups, related data
Paired T test
Interval Group comparison, 3 or more groups, independent data
ANOVA or MANOVA
Interval Group comparison, 3 or more groups, related data
Repeated measures ANOVA or Repeated measures MANOVA
what are the interval tests done when there are 3 or more groups and a difference is found
- Bonferroni
- Tukey
- Scheffe
- Dunn
- Dunnett
- Student-Newman-Keul
how do you decide b/t a Chi-squared and a Fisher’s exact test
- Chi-squared used for cell counts > 5
- Fisher’s exact test used with EXPECTED cell count of <5
what are the buzz words to know if data b/t comparison groups are related
- pre vs post
- before and after
- baseline vs end
what is the correlation test showing relationship or agreement b/t evaluators (consistency of “decisions” and “determinations”)
Kappa Statistic
describe the kappa interpretation
+1: the observers perfectly “classify” everyone exactly the same way
0: there is no relationship at all b/t the observers’ “classifications”, above the agreement that would be expected by chance
- 1: the observers “classify” everyone exactly the opposite of each other
Describe a Type 1 error
Rejecting the Null hypothesis when it is actually true and you should have accepted it
Describe a type 2 error
Not rejecting the Null hypothesis when it is actually False and you should have rejected it
what does the p value represent?
the probability of experiencing a type 1 error
-in other words it is the risk of being wrong if we reject the null hypothesis
what is often used now in place of the P value and what is the value of it
Confidence interval . . most of the time 95%
-states that we are 95% confident that the “true” difference or relationship between the groups is contained within the confidence interval range
what happens if the CI crosses 1.0
there is NO difference or it’s not significant
