The residents of a home have been complaining of eye, nose, and throat irritation and coughing, wheezing, chest pains, and bronchitis since they moved into their new home. After learning that urea-formaldehyde insulation was installed in the home, they have their home inspected for formaldehyde. The steady state concentration of formaldehyde was determined

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 .