2Chapter 2 Basic Information Major Points Scales of measurementScales of measurement VariablesVariables Random samplingRandom sampling NotationNotation Review questionsReview questions
3Chapter 2 Basic Information Scales of Measurement DefinitionDefinition Nominal scalesNominal scales Ordinal scalesOrdinal scales Interval scalesInterval scales Ratio scalesRatio scales What does it all mean?What does it all mean?
4Chapter 2 Basic InformationVariables Define variableDefine variable XProperty of an object or event that can take on different values Discrete variableDiscrete variable XVariable that can take on only a small set of possible values Continuous variableContinuous variable XVariable that can take on any value Cont.
5Chapter 2 Basic Information Variables --cont. Independent variablesIndependent variables XThose variables controlled by the experimenter Dependent variablesDependent variables XThose variables being measured XThe data or score
6Chapter 2 Basic Information Random Sampling DefineDefine Distinguish between random sampling and random assignmentDistinguish between random sampling and random assignment How to draw a random sampleHow to draw a random sample XA big hat XRandom number tables XWhy not just make them up in your head? A class demonstrationA class demonstration
7Chapter 2 Basic InformationNotation Variable namesVariable names XX and Y Individual valuesIndividual values XX i X versus X iX versus X i Summation notationSummation notation X X X X 2 X( X) 2 X XY X X Y XConstants
8Chapter 2 Basic Information Hypothetical data on family size by decade of 20th century
9Chapter 2 Basic Information Review Questions Give an example of a nominal, ordinal, interval, and ratio scale.Give an example of a nominal, ordinal, interval, and ratio scale. What kinds of scales would apply to hours of sunlight and quality of life?What kinds of scales would apply to hours of sunlight and quality of life? Why is random assignment more important than random sampling?Why is random assignment more important than random sampling? Cont.
10Chapter 2 Basic Information Review Questions -- cont. Why are X 2 and ( X) 2 different?Why are X 2 and ( X) 2 different? What happens when you multiply by a constant, or add a constant?What happens when you multiply by a constant, or add a constant?