What is a Survey?
Survey methodology involves the study of the sampling of individual units from a population and the associated survey data collection techniques, such as questionnaire construction and methods for improving the number and accuracy of responses to surveys.
Statistical surveys are undertaken with a view towards making statistical inferences about the population being studied, and this depends strongly on the survey questions used. Polls about public opinion, public health surveys, market research surveys, government surveys, and censuses are all examples of quantitative research that use contemporary survey methodology to answers questions about a population. Although censuses do not include a "sample," they do include other aspects of survey methodology, like questionnaires, interviewers, and nonresponse follow-up techniques. Surveys provide important information for all kinds of public information and research fields, like marketing research, psychology, health, and sociology.
Since survey research is almost always based on a sample of the population, the success of the research is dependent on the representativeness of the sample with respect to a target population of interest to the researcher.
What is an Experiment?
An experiment is an orderly procedure carried out with the goal of verifying, falsifying, or establishing the validity of a hypothesis. Experiments provide insight into cause-and-effect by demonstrating what outcome occurs when a particular factor is manipulated. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results in a method called the scientific method . A child may carry out basic experiments to understand the nature of gravity, while teams of scientists may take years of systematic investigation to advance the understanding of a phenomenon. Experiments can vary from personal and informal (e.g. tasting a range of chocolates to find a favorite), to highly controlled (e.g. tests requiring a complex apparatus overseen by many scientists that hope to discover information about subatomic particles). Uses of experiments vary considerably between the natural and social sciences.
Scientific Method
This flow chart shows the steps of the scientific method.
In statistics, controlled experiments are often used. A controlled experiment generally compares the results obtained from an experimental sample against a control sample, which is practically identical to the experimental sample except for the one aspect whose effect is being tested (the independent variable). A good example of this would be a drug trial, where the effects of the actual drug are tested against a placebo.
When is One Technique Better Than the Other?
Surveys and experiments are both techniques used in statistics. They have similarities, but an in depth look into these two techniques will reveal how different they are. When a businessman wants to market his products, it's a survey he will need and not an experiment. On the other hand, a scientist who has discovered a new element or drug will need an experiment, and not a survey, to prove its usefulness. A survey involves asking different people about their opinion on a particular product or about a particular issue, whereas an experiment is a comprehensive study about something with the aim of proving it scientifically. They both have their place in different types of studies.