OPERATIONALLY DEFINED

Sociologyindex, Sociology Books 2009

To define some concept of study in such a way that it can be observed and measured. For example, "well being" might be measured by asking people to rate their overall satisfaction with their life style, or "anti-social behaviour" might be measured by frequency of arrest or criminal prosecution.

Operational definitions require that we first specify our constructs; developing reliable and valid operations is the last step of specifying constructs when we are designing our own studies. The science of psychology tries to develop explanations of human behavior through objective observations. The procedures or operations that we use to objectively measure a variable are known as its operational definition. The operational definition gives the variable meaning within a particular study. The features of a operational definition vary depending on the study design.

Operational Definitions Operationally Defined 
Stuart C. Dodd, Ethel Shanas
The American Journal of Sociology, Vol. 48, No. 4 (Jan., 1943), pp. 482-491
Abstract: This paper attempts to meet the challenge of defining operational definitions operationally. A definition is operational to the extent that it specifies the procedure for identifying or generating the definiendum and finds high reliability for the definition. The logical form of this definition, its gradational phrasing, the concepts of "procedure" and "reliability," and the two types of operational definitions are commented upon. The importance of reliability for scientific work is stressed. Experimental procedures for measuring the utility, the reliability, the validity, and the usage of any concepts defined are suggested and proposed as criteria for the excellence of any sociological definition. - jstor.org

Historic Ideals Operationally Defined 
Stuart C. Dodd
The Public Opinion Quarterly, Vol. 15, No. 3 (Autumn, 1951), pp. 547-556
Abstract: Moment formulas can be used as an aid in defining important human ideals and values in measurable terms. Such classic ideals as "liberty, equality, and fraternity" can be redefined as a moment of some one order. Eleven such conceptsare analyzed here as examples of the exactness of meaning which the moments can yield. - jstor.org

Expression profile of an operationally-defined neural stem cell clone.
Parker MA, Anderson JK, Corliss DA, Abraria VE, Sidman RL, Park KI, Teng YD, Cotanche DA, Snyder EY. 
Department of Otolaryngology, EN41, Children's Hospital-Boston, 300 Longwood Avenue, Boston, MA 02115, USA. mark.parker@childrens.harvard.edu
Abstract: Neural stem cells (NSCs) are the most primordial and least committed cells of the nervous system, the cells that exist before regional specification develops. Because immunocytochemically-detectable markers that are sufficiently specific and sensitive to define an NSC have not yet been fully defined, we have taken the strong view that, to be termed a "stem cell" in the nervous system--in contrast to a "progenitor" or "precursor" (whose lineage commitment is further restricted)--a single neuroectodermally-derived cell must fulfill an operational definition that is essentially similar to that used in hematopoiesis. In other words, it must possess the following functional properties: (1) "Multipotency", i.e., the ability to yield mature cells in all three fundamental neural lineages throughout the nervous system--neurons (of all subtypes), astrocytes (of all types), oligodendrocytes--in multiple regional and developmental contexts and in a region and developmental stage-appropriate manner. (2) The ability to populate a developing region and/or repopulate an ablated or degenerated region of the nervous system with appropriate cell types. (3) The ability to be serially transplanted. (4) "Self-renewal", i.e., the ability to produce daughter cells (including new NSCs) with identical properties and potential. Having identified a murine neural cell clone that fulfills this strict operational definition--in contrast to other studies that used less rigorous or non-operational criteria for defining an NSC (e.g., the "neurosphere" assay)--we then examined, by comparing gene expression profiles, the relationship such a cell might have to (a) a multipotent somatic stem cell from another organ system (the hematopoietic stem cell [HSC]); (b) a pluripotent stem cell derived from the inner cell mass and hence without organ assignment (an embryonic stem cell); (c) neural cells isolated and maintained primarily as neurospheres but without having been subjected to the above mentioned operational screen ("CNS-derived neurospheres"). ESCs, HSCs, and operationally-defined NSCs--all of which have been identified not only by markers but by functional assays in their respective systems and whose state of differentiation could be synchronized--shared a large number of genes. Although, as expected, the most stem-like genes were expressed by ESCs, NSCs and HSCs shared a number of genes. CNS-derived neurospheres, on the other hand, expressed fewer "stem-like" genes held in common by the other operationally-defined stem cell populations. Rather they displayed a profile more consistent with differentiated neural cells. (Genes of neural identity were shared with the NSC clone.) Interestingly, when the operationally-defined NSC clone was cultured as a neurosphere (rather than in monolayer), its expression pattern shifted from a "stem-like" pattern towards a more "differentiated" one, suggesting that the neurosphere, without functional validation, may be a poor model for predicting stem cell attributes because it consists of heterogeneous populations of cells, only a small proportion of which are truly "stem-like". Furthermore, when operational definitions are employed, a common set of stem-like genes does emerge across both embryonic and somatic stem cells of various organ systems, including the nervous system. - ncbi.nlm.nih.gov