2.1.1 Levels of Measurement of Variables -- 2.1.2 Application Activity: Practice in Identifying Levels of Measurement -- 2.1.3 Dependent and Independent Variables -- 2.1.4 Application Activities: Practice in Identifying Variables -- 2.1.5 Summary of Variables -- 2.1.6 Fixed versus Random Effects (Advanced Topic) -- 2.2 Understanding Hidden Assumptions about How Statistical Testing Works -- 2.2.1 Hypothesis Testing -- 2.2.2 Application Activities: Creating Null Hypotheses -- 2.2.3 Who Gets Tested? Populations versus Samples and Inferential Statistics -- 2.2.4 What Does a P-Value Mean? -- 2.2.5 Effect Sizes -- 2.2.6 Understanding Statistical Reporting -- 2.2.7 Application Activities: Understanding Statistical Reporting -- 2.2.8 The Inner Workings of Statistical Testing -- 2.2.9 Application Activity: The Inner Workings of Statistical Testing -- 2.2.10 Summary of Hidden Assumptions -- 2.3 Parametric and Non-Parametric Statistics -- 2.3.1 Why Robust Statistics? -- 2.4 Summary -- 3 Describing Data Numerically and Graphically and Assessing Assumptions for Parametric Tests -- 3.1 Numerical Summaries of Data -- 3.1.1 The Mean, Median and Mode -- 3.1.2 Standard Deviation, Variance and Standard Error -- 3.1.3 Confidence Intervals -- 3.1.4 The Number of Observations and Other Numerical Summaries You Might Want to Report -- 3.1.5 Reporting Numerical Summaries -- 3.1.6 Data for this Chapter -- 3.2 Using SPSS to Get Numerical Summaries -- 3.2.1 Obtaining Numerical Summaries with SPSS and Splitting Groups -- 3.2.2 Application Activities for Numerical Summaries in SPSS -- 3.3 Using R to get Numerical Summaries -- 3.3.1 Basic Descriptive Statistics in R -- 3.3.2 Application Activities for Numerical Summaries in R -- 3.4 Satisfying Assumptions for Parametric Tests -- 3.5 Graphic Summaries of Data: Examining the Shape of Distributions for Normality -- 3.5.1 Histograms