CI for ICC

[Bill Wu]

How does SPSS calculate confidence interval for ICC?  I have the following output.
Thanks in advance.

Bill

ANOVA

		Sum of Squares	df	Mean Square	F	Sig
Between People		76.867	19	4.046
Within People	Between Items	9.567	5	1.913	3.058	.013
	Residual	59.433	95	.626
	Total	69.000	100	.690
Total		145.867	119	1.226
Grand Mean = 2.6333

Intraclass Correlation Coefficient
	Intraclass Correlationa	95% Confidence Interval		F Test with True Value 0
		Lower Bound	Upper Bound	Value	df1	df2	Sig
Single Measures	.477b	.290	.690	6.467	19	95	.000
Average Measures	.845c	.710	.930	6.467	19	95	.000
Two-way mixed effects model where people effects are random and measures effects are fixed.
a. Type C intraclass correlation coefficients using a consistency definition-the between-measure variance is excluded from the denominator variance.
b. The estimator is the same, whether the interaction effect is present or not.
c. This estimate is computed assuming the interaction effect is absent, because it is not estimable otherwise.

 

                
           


       

            

[Marta Garcia-Granero]

You can find all that information here:

http://support.spss.com/ProductsExt/SPSS/Documentation/Manuals/15.0/SPSS 15.0 Algorithms.pdf (pages 623 to 631).

HTH,
Marta GG


El 14/02/2011 23:14, Bill Wu escribió:

How does SPSS calculate confidence interval for ICC?  I have the following output.
Thanks in advance.

Bill

ANOVA

		Sum of Squares	df	Mean Square	F	Sig
Between People		76.867	19	4.046
Within People	Between Items	9.567	5	1.913	3.058	.013
	Residual	59.433	95	.626
	Total	69.000	100	.690
Total		145.867	119	1.226
Grand Mean = 2.6333

Intraclass Correlation Coefficient
	Intraclass Correlationa	95% Confidence Interval		F Test with True Value 0
		Lower Bound	Upper Bound	Value	df1	df2	Sig
Single Measures	.477b	.290	.690	6.467	19	95	.000
Average Measures	.845c	.710	.930	6.467	19	95	.000
Two-way mixed effects model where people effects are random and measures effects are fixed.
a. Type C intraclass correlation coefficients using a consistency definition-the between-measure variance is excluded from the denominator variance.
b. The estimator is the same, whether the interaction effect is present or not.
c. This estimate is computed assuming the interaction effect is absent, because it is not estimable otherwise.