Scatter Plot

Scatter Plot1Scott Davis, QI Coordinator Tacoma Pierce County Health Department7/12

Scatter PlotWhen would I use this tool?You want to see if there is a relationship between 2 continuous variablesYou want to test a theory

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Scatter Plot3Continuous Variable ScaleContinuous Variable ScaleData plotted at intersection for each caseIndependent variableDependent Variable

Scatter PlotTypes of Relationships4NegativePositiveComplexNone

Scatter PlotExample Positive correlation without unlikely relationship5Price per 5th

Scatter PlotExample Negative (complex) correlation with possible causal relationship6Days to deliverDoses Ordered

Scatter PlotBewareAssuming correlation is necessarily a causal relationshipOver interpreting a vague correlationMaking inferences with too little data7

Scatter PlotSteps by handClarify the relationship you are trying to establishGather at least 15 data points and preferably much moreCreate axes for each variable with proportional scalesThe variable you assume to be causal will go on the horizontal axis (generally)Plot data

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Scatter PlotSteps using ExcelClarify the relationship you are trying to establishGather at least 15 data points and preferably much moreEnter data in side by side columnsChoose scatter graph

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