Surveys and Experiments

It is important to point out that there are two major methods of collecting data:

A. Surveys:

A Survey refers to the collection of data when no special control is exercised over any factors influencing the variable of interest. The totality of elements (persons, farms, cities) under study is called the population. A survey that includes every element in the population is called a census. A sample is a portion of the population.

B. Experiments:

The term experiment refers to the collection of data when control is exercised over one or more factors to determine their influence on the variable of interest.

C. Surveys vs. Experiments

Both surveys and experiments can be extremely useful for studying the effects of one or more factors on the variable of interest. Experiments, however, provide stronger evidence of these effects than surveys.

D. Measurement Procedures for obtaining data in surveys:

1. Observation - involves direct measurement of an ongoing activity.

2. Personal Interview - an interviewer asks questions that are printed on a questionnaire and records the respondents' answers on the questionnaire form.

3. Self-enumeration - a measurement procedure in which the respondent is provided with a questionnaire to complete.