An investigator begins a research study after evolving ideas from a specific theory, which is an integrated set of statements for explaining various phenomena. Because a theory is too general to test, the investigator devises a hypothesis, or testable prediction, from the theory, and tests this instead. The results of the research study either disprove or do not disprove the hypothesis. If disproved, the investigator cannot make predictions based on the hypothesis, and must question the accuracy of the theory. If not disproved, the scientist can make predictions based on the hypothesis.
A goal of sociological research is to discover the similarities, differences, patterns, and trends of a given population. Members of a population who participate in a study are subjects or respondents. When the characteristics of a sample of the population are representative of the characteristics of the entire population, scientists can apply, or generalize, their findings to the entire population. The best and most representative sample is a random sample, in which each member of a population has an equal chance of being chosen as a subject.
In quantitative research, information collected from respondents (for example, a respondent's college ranking) is converted into numbers (for example, a junior may equal three and a senior four). In qualitative research, information collected from respondents takes the form of verbal descriptions or direct observations of events. Although verbal descriptions and observations are useful, many scientists prefer quantitative data for purposes of analysis.
To analyze data, scientists use statistics, which is a collection of mathematical procedures for describing and drawing inferences from the data. Two types of statistics are most common: inferential, used for making predictions about the population, and descriptive, used for describing the characteristics of the population and respondents. Scientists use both types of statistics to draw general conclusions about the population being studied and the sample.
A scientist who uses a questionnaire or test in a study is interested in the test's validity, which is its capacity to measure what it purports to measure. He or she is also interested in its reliability, or capacity to provide consistent results when administered on different occasions.
Cliffs Notes Online