If you sell Discovery Toys, World Book Encyclopedias, or any at-home shopping service geared towards young children, a properly fine-tuned list will cut out most of your wasted prospecting time and allow you to make more appointments in less time. A Discovery Toys rep can select homes with children aged 1-4 years old. World Book Encyclopedia sales reps can market directly to parents with children in grades 1-4.
To make the prospecting even better, you can select households with incomes greater than 30K, and you can even select homeowners rather than people living in apartments. Using a finely selected list will help weed out the 98% of your potential universe who really have little or no need for your services or products.
Drawback: The list compilers only pick up 85% of the potential universe in your area. And the 85% is accurate for the head of household's name, approximate income, type of dwelling, and age group. Many times the presence of children in the household is missed by the list companies (you generally have to fill out a survey or order something for children to show up in a presence of children file). My experience with these lists tells me that only about 50% of the families with children are listed as having children.
On the bright side, though, the families that are listed have either (a) responded to some form of direct marketing solicitation where they were asked questions about their children or (b) joined a club (book, toy or otherwise) that requested info on children, or (c) they actively purchased items from children's catalogues. The people on these lists will be more receptive to offers than other prospects who, for one reason or another, never made it onto the rosters.