what is the sum contrast in the experimental design? what is the difference between sum and contrast what is the difference between sum and treatment contrast what does sum coding mean in a contrast matrix why is the sum coding and the treatment coding different why is it important to use the sum coding of contrasts why is contrast a treatment what is the difference between sum and treatment in graphing what is the difference between treatment and contrast coding what is the treatment contrasts which is an example of a sum-coding technique? what is contrast coding what is treatment contrast which coding system is used for contrasts what does it mean when contrasts are negative why is the contrast matrix negative in the sum coding system? what is the contrast in coding why is the sum contrast more valid why is the contrast matrix a treatment or treatment coding system what is the difference between sum and treatment contrasts