Nested Design Comparison of 2 Shampoo Formulations on Hair Combability M.L. Garcia and J. Diaz (1976). “Combability Measurements on Human Hair,” Journal of the Society of Cosmetic Chemists, Vol.27 pp

Data Description 2 Formulations of Shampoo (A and B) 16 Hair Swatches Prepared (8 for A, 8 for B) 5 Test Runs Made per Swatch (Replicates) Combability Measurements made before and after shampooing (we consider only AFTER here) Shampoo Treated as FIXED Factor, Swatch RANDOM N=2x8x5=80 Measurements

Statistical Model Note: For Computational purposes, we will label the swatches 1,…,16 and not 1,…,8 separately for each shampoo

Data

Summary Statistics

Sums of Squares

ANOVA – Tests of Factor Effects H 0 :      H A :    ≠   T.S.: F Form = (P=0.7390) Conclude no formulation differences on combability H 0 :  b 2 = 0 H A :  b 2 > 0 T.S. F Swatch(F) = 9.43 (P=.0000) Conclude Swatch effects vary with respect to combability