Statistics

301/10am

Angela Mazza Homework #1 08/27/10

Surveys are useful and powerful tools for both public and private organizations that need to know characteristics and opinions of people they serve. When the survey made its first appearance to the public, it was regarded as too complex and costly to be conducted by nonprofessional surveyors. However, throughout the years, doing surveys by mail, telephone, and the drop-off method has come of age. In fact, surveys are now viable alternatives to the once standard and expensive face-to-face interview; but are not commonly used. People with little research experience or background knowledge can achieve a credible survey.

In order to create an accurate survey, a series of key questions need to be answered. These questions include but are not limited to how many people are required for a valid survey, how should the sample be selected and how accurate will the results be? An initial survey a person might try to answer these questions is a sample survey. The purpose of a sample survey is to obtain information from a few respondents in order to describe the characteristics of hundreds, thousands, or even millions. The same is selected in such a way that it represents the entire population; that is, observations from the sample can be generalized to the larger group. However, it is important to remember that estimates based on samples are subject to sampling error, a potential error that occurs when surveyors interview only a sample, instead of the entire population. Surveys can be used in a scientific way to realize the great benefits of interviewing a representative sample instead of the whole population. To make accurate estimates based on human sample, four requirements need to try to be meet, (1) the sample is large enough to yield the desired level of precision, (2) everyone in the population has an equal (or known) chance of being selected for the sample, (3) questions area asked in ways that enable the...