What is the same about all the elements in a single group on the periodic table? The number of isotopes they form
The number of valence electrons in an atom
The number of core electrons in an atom
Their atomic mass

The independent variable is the type of music.the dependent variable is the pulse rate.the intervening variable is the age of the subject.if the mother does not like rock, her pulse is likely to not increase.the same might be true for the sister.the friend may like rap and gets excited.to establish cause/effect relationship, all of the subjects must be consistent.hope i .

Sorry i dont understand the question can you rephase it?