### What Statistical Test To Use:

I memorized this table and wrote it out on my noteboard during the test. It makes it easy to pick out which test without much mental effort

Type of Data | 2 Independent Samples | Related or Paired Samples | 3 or More Independent Samples | 3 or More Related Samples | Measures of Correlation |

Nominal Example: male/female, yes/no, dead/alive | Chi-Square Fisher’s Exact (for small samples) | McNemar test | Chi-Square for K-independent t-samples | Cochran Q | contingency coefficient |

Ordinal Example: Class I, II, II Heart failure | Mann Whitney U Willcoxen Rank Sum | Sign test Willcoxen Signed Rank | Kruskal Wallis one way ANOVA | Friedman 2 way ANOVA | Spearman Kendall rank Kendell COE |

Continuous (aka “parametric”) Example: temperature, heart rate, blood pressure | Student T-test Mann Whitney U (only if parametric with outliers) | Paired t-test | 1-way ANOVA | 2-way ANOVA | Pearson correlation |

### Study Type Strength or Weakness:

They may ask what kind of study would you use for X problem.

*Top is the highest quality, the bottom is the least

**Cohort and cross-sectional**studies are usually prospective, case-control and case-report are usually retrospective.**Cohort studies**are best suited determining the**association**between exposures/factors and diseases/conditions (prospective. You follow a cohort and see if they get the disease).**Case-control**studies are best to determine the association between a**rare event**and a potential cause (retrospective. You see the rare event and work backward because the event is too rare to find in enough numbers in a random cohort).**Cross-sectional**studies are data collected from a population, or subset, at one specific point in time.**Survival analysis**– time to an event, not just death or MI, etc. Can be anything. Kaplan Meir curves estimate the percentage of people saved per time

### Is it Intention to Treat or Per Protocol?

**Intention to treat**: Analyze data from all randomized patients, regardless of completion of the trial. This increases external validity (is this applicable to the real world)**Per-protocol**: This increase internal validity (is this a well-done study for whatever the hypothesis is). Only count those who followed the trial to completion. The reflects the actual treatment, not real-world results.