One difference between a repeated measures design and a matched samples design is that

a) only one design is a type of related sample design

b) only one design increases the power to observe an effect

c) only one design involves observing the same participants in each group

d) only one design eliminates between-persons variability

a researcher asks a sample of brothers and sisters to rate how positive their family environment was during childhood. in this study, the differences in ratings between each brother and sister pair were compared. the type of design described here is called a :

a) repeated measures design

b) matched samples design

c) both a and b