Chapter 6.2, Problem 6.31E

(a)

To determine

To find out that was the experiment double-blind or not and explain why this is important.

Answer to Problem 6.31E

It was not double-blind.

Explanation of Solution

The experiment was not double-blind. The people weighing the babies maybe did not know whether the mothers had received an ultrasound, but the mothers themselves knew, which could have effected how they behaved during the rest of their pregnancy.

(b)

To determine

To identify did the experimental design take the placebo effect into account and explain why this is important.

Answer to Problem 6.31E

No.

Explanation of Solution

The experiment did not take the placebo effect into account. This is important because the placebo effect could explain why mothers with ultrasounds had heavier babies.

(c)

To determine

To describe an improved design for this experiment based on part (a) and (b).

Explanation of Solution

The improved design is as;

Treat all mothers as if they were having an ultrasound, but turn the ultrasound machine off for some mothers.