Statistics Ch.1:Variables & Measurement

Types

• Statistics:– Descriptive – Inferential

• Data: Collections of observations– Population– Sample

Data & Measurement

• Qualitative Data -> Nominal Measurement– Names, categories, groups, attitudes…

• Ranked Data -> Ordinal Measurement– Placement, relative standing, Olympic medals…

Data & Measurement

• Quantitative Data-> Interval/Ratio Measurement

– Amount or count, equivalent differences:

• Weight, height, temperature, test scores, income…

• Ratio = Interval + an absolute 0

Variables

• Discrete vs Continuous

• Independent vs Dependent

• Confounding

Experimental Design

• Experiments– Random assignment

• Observational Studies– Random sampling

What is the pattern of scores?• Graphs often make it easier to see certain

characteristics and trends in a set of data.

– Graphs for quantitative data.• Stem and Leaf Display• Histogram• Frequency Polygon

– Graphs for qualitative data.• Bar Chart• Pie Chart

number/count

class/category

Shapes of Distributions

Misleading Graphs

HW 1• Appendix A: Pretest, read, Posttest

• Find a study (internet, paper, tv, etc)– Summarize in a paragraph– Identify key terms from ch. 1:

• Population or sample?• Inferential or descriptive?• Random sampling/assignment?• Data & measurement?• Discrete/continuous variable(s)?• Experiment/observational study?• Independent, dependent, confounding variables