This page will perform an analysis of covariance for four independent samples, cross-tabulated according to two independent variables, A and B, where

• A₁ and A₂ represent two quantitative or categorical levels of the independent variable A;
  
• B₁ and B₂ represent two quantitative or categorical levels of the independent variable B;
  
• DV = the dependent variable of interest; and
  
• CV = the concomitant variable whose effects one wishes to bring under statistical control.

Procedure: For each sample, enter the paired values of CV and DV in the cells of the designated columns, beginning in the top-most cell of each column. Within any particular column, pressing the "tab" key will take you down to the next cell in the column. After all data have been entered, click the "Calculate" button. ~~ If you wish to perform another analysis with a different set of data: click the "Reset" button if the value of n for the largest of your new samples is or smaller; click the "Reload" button if the value of n for the largest of the new samples is greater than .

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Data Entry:
  CV = concomitant variable
  DV = dependent variable_Q

		B1			B2
		CV	DV		CV	DV
A1
A2

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Dependent Variable:
Values of n for Cells and Marginals_Q

		B1	B2		Totals
A1
A2
Totals

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Dependent Variable: Observed Means_Q

		B1	B2		Totals
A1
A2
Totals

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Dependent Variable: Adjusted Means_Q

		B1	B2		Totals
A1
A2
Totals

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Aggregate Correlation within Samples: CV vs DV_Q

r =

r2 =

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ANCOVA Summary_Q

Source	SS	df	MS	F	P
adjusted A
adjusted B
adjusted AxB
adjusted error

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Test for homogeneity of regressions:_Q

Source	SS	df	MS	F	P
between regressions
remainder
adjusted error

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©Richard Lowry 2001-
All rights reserved.

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