Scientific inquiry is grounded in the inference process. This process is used for the development and testing of various propositions largely through the double movement of reflective thinking. Reflective thinking consists of sequencing induction and deduction in order to explain inductively (by hypothesis) a puzzling condition. In turn, the hypothesis is used in a deduction of further facts that can be sought to confirm or deny the truth of the hypothesis. Researchers think of the doing of science as an orderly process that combines induction, deduction, observation, and hypothesis testing into a set of reflective thinking activities. Although the scientific method consists of neither sequential nor independent stages, the problem-solving process that it reveals provides insight into the way research is conducted.
Scientific methods and scientific thinking are based on concepts, the symbols we attach to bundles of meaning that we hold and share with others. We invent concepts to think about and communicate abstractions. We also use higherlevel concepts—constructs—for specialized scientific explanatory purposes that are not directly observable. Concepts, constructs, and variables may be defined descriptively or operationally. Operational definitions must specify adequately the empirical information needed and how it will be collected. In addition, they must have the proper scope or fit for the research problem at hand. Concepts and constructs are used at the theoretical levels; variables are used at the empirical level. Variables accept numerals or values for the purpose of testing and measurement. They may be classified as explanatory, independent, dependent, moderating, extraneous, and intervening.
Propositions are of great interest in research because they may be used to assess the truth or falsity of relationships among observable phenomena. When we advance a proposition for testing, we are hypothesizing. A hypothesis describes the relationships between or among variables. A good hypothesis is one that can explain what it claims to explain, is testable, and has greater range, probability, and simplicity than its rivals. Sets of interrelated concepts, definitions, and propositions that are advanced to explain and predict phenomena are called theories. Models differ from theories in that models are analogies or representations of some aspect of a system or of the system as a whole. Models are used for description, prediction, and control.
