Most couples who want to start a family encounter few biological difficulties. For many, however, it is not so simple. Some of these couples have used Assisted Reproductive Technology (ART) since 1981, usually through the transfer of fertilized eggs into the woman's uterus. The technology is not 100% effective however, and it is a difficult decision to go through the expensive treatment. Determining the chances of success is a primary consideration in making that decision.

A successful ART treatment results in the delivery of a live-born infant. There are many types of ART, which you can learn about in the following report. We will at look one part of the picture: the effect of a woman's age on achieving pregnancy using ART.

The Center for Disease Control's (CDC) 1995 National Report contains line graphs and bar charts to answer some of these questions.

The report makes the statement that

The national data are useful because they can give potential ART users an idea of their average chances of success. Average chances, however, do not necessarily apply to a particular individual or couple. People considering ART should consult their physician to discuss all the factors that apply in their particular case.

This is an important concept, and it affects everything you will learn about statistics, not only the probability of ART success. You have probably heard the old joke:

One out of five people are crazy. Think of four of your friends. If they're ok, then it's you.

Even if the first statement is true, the conclusion certainly doesn't follow. In statistical terms, why is it that the conclusion isn't true? It is exactly that kind of reasoning that the CDC is warning readers against.

The following charts, graphs, and tables present a picture of the 1995 Assisted Reproductive Technology success rates

The age of the prospective mother is the most important factor affecting the chances of a live birth when the woman's own eggs are used. The following graph (from the CDC) displays the live birth rate for women who used ART in 1995. What can you say, after looking at the data, about the effect of age on success rate? What is the success rate for women under 34? for women over 47?