Determination of Sample Size: A Review of Statistical Theory

Determination of Sample Determination of Sample Size: A Review of Size: A Review of Statistical TheoryStatistical Theory

Chapter 13Chapter 13

Sample v. PopulationSample v. Population

InferentialInferential DescriptiveDescriptive Sample statisticsSample statistics Population parametersPopulation parameters

TablesTables

Frequency distributionFrequency distribution Percentage distributionPercentage distribution ProbabilityProbability ProportionProportion

Measures of Central TendencyMeasures of Central Tendency

MeanMean MedianMedian ModeMode

Measures of DispersionMeasures of Dispersion

RangeRange– FormulaFormula

Deviation (Variance)Deviation (Variance)– FormulaFormula

Standard DeviationStandard Deviation– FormulaFormula

The Normal DistributionThe Normal Distribution

Three CharacteristicsThree Characteristics Standardized Normal DistributionStandardized Normal Distribution

– Why do I have to know this?Why do I have to know this?– What does it mean?What does it mean?– VariableVariable– FormulaFormula– ExampleExample

Population Distribution, Sample Population Distribution, Sample Distribution, and Sampling Distribution, and Sampling

DistributionDistribution Population: Population: µµ ơơ Sample: Sample: SS

Sampling DistributionSampling Distribution– Standard Error of the MeanStandard Error of the Mean– SymbolSymbol– FormulaFormula

Central Limit TheoremCentral Limit Theorem

As sample size increases, the As sample size increases, the distribution of the mean, of any distribution of the mean, of any sample approaches a normal sample approaches a normal distribution.distribution.

Estimation of ParametersEstimation of Parameters

Point EstimatesPoint Estimates– What is it?What is it?

Confidence IntervalsConfidence Intervals– Question #10, page 343Question #10, page 343

Sample Size for MeansSample Size for Means

Sample ErrorSample Error– FormulaFormula– FactorsFactors

VarianceVarianceMagnitude of error (confidence interval)Magnitude of error (confidence interval)Confidence levelConfidence level

Sample Size for MeansSample Size for Means

FormulaFormula Question #11 page 343Question #11 page 343 Question #12 page 343Question #12 page 343

Sample Size for ProportionsSample Size for Proportions

Standard Error for ProportionStandard Error for Proportion– FormulaFormula

Confidence intervalConfidence interval– FormulaFormula

Sample SizeSample Size– FormulaFormula