EBM Exam 1

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  1. Type of data in non-parametric tests
    • nominal
    • ordinal
  2. Nominal data
    • mutually exclusive
    • yes/no
    • male/female
  3. Chi squared test
    • two samples
    • at least 40 observations (20 per group)
    • nominal data
  4. Fisher's Exact
    • similar to chi squared but for smaller sample sizes
    • two groups
    • less than 5 per group
    • usually for uncommon events
    • for nominal data
  5. Mantel-Haenszel
    • three or more groups
    • series of chi-squares
    • totals are added up and overall chi-square is calculated
    • for nominal data
  6. McNemar's Test
    • similar to chi-squared
    • data is paired (there is a control or pt serves as their own control)
    • for nominal data
  7. Ordinal Data
    • categorical
    • ranked on a scale with no consistent distance between values
    • ex. pain scale
  8. Mann-Whitney U/Wilcoxon Rank Sum
    • two groups
    • ranks individual observations rather than values
    • data values are assigned from lowest to highest
    • the sum of the data is totalled at the bottem fo the chart
    • (rank pain 1-6 and the group with lower number has better pain control)
  9. Kruskal-Wallis
    • for observational data
    • for multiple comparisons
    • if average ranks are close H0 is not rejected
    • post hock analysis needed to determine difference between treatment groups
    • Friedman's test is similar for 3 or more groups
  10. Wilcoxon signed rank
    • similar to paired t-test
    • for paired data
    • differences arranged in order of absolute value
    • observations of 0 are excluded
    • average rank is assigned
  11. continuous data
    • ratio or interval data
    • placed on a numerical scale with infinite amount of values
    • equal distance between those values
  12. T-test
    • "student's T-test"
    • compares the mean of a population to the known mean
    • 2 groups
    • variance of both groups must be equal
    • interval or ratio data
  13. ANOVA
    • for interval or ratio data
    • 3 or more groups
  14. ANCOVA
    • for ordinal or ratio data
    • similar to ANOVA but controls for covariates
    • ex. study effect of bisphosphonates on osteoprosis, but age and exercise are also factors, control for these to see the difference the drug makes
  15. Paired T-test
    • for interval or ratio data
    • compare the mean difference between 2 groups that are paired or matched
    • can be used when the subject is their own control (cross over)
  16. ANOVA for repeated measures
    • similar to ANOVA but measures subjects under a different set of conditions in a repeated manner
    • ex. pt with osteoporosis screened anually for next 5 years for changes in BMD
  17. correlation
    • measure of association between 2 variables
    • r ranges from -1 to 1
    • independant variable is x
    • dependent variable is y
  18. regression
    • 0.9-1 = excellent correlation, probably predictive
    • 0.7-0.9 = good correlation, may be predictive
    • 0.6-0.7 = good correlation, may not be predictive
    • <0.6 considered not predictive
  19. Kaplan Meier survival analysis
    • survival analysis as a function of time
    • interval or ratio data
    • time on the x axis
  20. Survivial analysis censored vs. uncensored
    censored means incomplete data, but is analagous to intent-to-treat
  21. Post-Hoc Analyses
    • performed after primary analysis when H0 has been rejected
    • considered inferior to planned comparisons
    • often easier to understand
Card Set
EBM Exam 1
Biostats 3
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