Elements of Inferential StatisticsElements of Inferential Statistics

module 16module 16

ReadingReading

•• read Chapter 8read Chapter 8

Elements of Inferential StatisticsElements of Inferential Statistics

1-Sample Difference of Means Tests1-Sample Difference of Means Tests

Small SampleSmall Sample

Issues in Inferential TestingIssues in Inferential Testing& Test Selection& Test Selection

•• degrees of freedomdegrees of freedom

Issues in Inferential TestingIssues in Inferential Testing& Test Selection& Test Selection

•• sampling issues and inferentialsampling issues and inferentialtestingtesting–– common characteristicscommon characteristics

–– common assumptionscommon assumptions•• randomnessrandomness

•• independenceindependence

Issues in Inferential TestingIssues in Inferential Testing& Test Selection& Test Selection

•• artificial sampleartificial sample

•• natural sample (population)natural sample (population)–– inferential analysis has to be usedinferential analysis has to be used

with great cautionwith great caution

Issues in Inferential TestingIssues in Inferential Testing& Test Selection& Test Selection

•• inferential test selectioninferential test selection

Type of question: Differences Nature of relationship Nature Type of question: Differences Nature of relationship Natureof relationshipof relationship

SCALESCALE 1 sample1 sample matched-pairsmatched-pairs 2 samples2 samples 2 variables2 variablesmultiple variablesmultiple variables

NOMINALNOMINAL

ORDINALORDINAL

INTERVAL/ INTERVAL/ 1 sample1 sample

RATIO RATIO differencedifference

of means of means

( Z or t ) ( Z or t )

1 sample 1 sample

difference difference

of proportions of proportions

( Z ) ( Z )

Issues in Inferential TestingIssues in Inferential Testing& Test Selection& Test Selection

•• nonparametric or distribution-nonparametric or distribution-free testsfree tests