A disadvantage of observation is that many variables of interest in development cannot be measured in a valid way by watching people.

When problems exist between parents and children, their problems are usually BEST handled by __________

a. psychoanalysis b. family therapy c. operant conditioning d. individual therapy

In order to calculate the z test, one must know

a. the sample's true standard deviation b. the amount of sampling error present c. the parameter mean, the parameter standard deviation and the sample mean d. the exact amount of bias contained in the sample