vi Biostatistics For Dummies

CHAPTER 3: Getting Statistical: A Short Review of

Basic Statistics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Taking a Chance on Probability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Thinking of probability as a number. . . . . . . . . . . . . . . . . . . . . . . . . . 30

Following a few basic rules of probabilities. . . . . . . . . . . . . . . . . . . . 30

Comparing odds versus probability. . . . . . . . . . . . . . . . . . . . . . . . . . 32

Some Random Thoughts about Randomness . . . . . . . . . . . . . . . . . . . . 33

Selecting Samples from Populations. . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Recognizing that sampling isn’t perfect. . . . . . . . . . . . . . . . . . . . . . . 34

Digging into probability distributions. . . . . . . . . . . . . . . . . . . . . . . . . 35

Introducing Statistical Inference. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Statistical estimation theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Statistical decision theory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Honing In on Hypothesis Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Getting the language down. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Testing for significance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Understanding the meaning of “p value” as the result of a test. . . 42

Examining Type I and Type II errors. . . . . . . . . . . . . . . . . . . . . . . . . . 42

Grasping the power of a test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Going Outside the Norm with Nonparametric Statistics. . . . . . . . . . . . 47

PART 2: EXAMINING TOOLS AND PROCESSES. . . . . . . . . . . . . . . 51

CHAPTER 4: Counting on Statistical Software . . . . . . . . . . . . . . . . . . . . . . 53

Considering the Evolution of Statistical Software. . . . . . . . . . . . . . . . . . 54

Comparing Commercial to Open-Source Software. . . . . . . . . . . . . . . . 54

Checking Out Commercial Software. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

SAS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

SPSS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Microsoft Excel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Online analytics platforms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Focusing on Open-Source and Free Software. . . . . . . . . . . . . . . . . . . . . 58

Open-source software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Other free statistical software. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Choosing Between Code-based and Non–Code-Based Methods . . . . 60

Storing Data in the Cloud. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

CHAPTER 5: Conducting Clinical Research. . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Designing a Clinical Trial. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Identifying aims, objectives, hypotheses, and variables. . . . . . . . . 62

Deciding who is eligible for the study. . . . . . . . . . . . . . . . . . . . . . . . . 64

Choosing the structure of a clinical trial. . . . . . . . . . . . . . . . . . . . . . . 65

Using randomization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Selecting the analyses to use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67