JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Biometrika Trust is collaborating with JSTOR to digitize, preserve and extend access to Biometrika. SUMMARYThe jackknife method of investigating and reducing the bias in nonlinear estimates of parameters is applied to stratified samples from a multivariate population of finite size. Attention is focused on estimators that can be expressed as functions of sample means. Examples are estimators of ratios and some estimators of products.

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Specification of teacher competencies is a most crucial aspect of designing a competency-based teacher education program. The purpose of this article is to examine several issues related to specifying teacher competencies, specifically, the bases from which competencies might be specified, the kinds of competencies which might be specified, the persons who might be involved in specifying competencies, and the processes which might be used in specifying competencies. The &dquo;Why&dquo; of Specifying Teacher Competencies One dictionary defines competent as being &dquo; ... fitted, suitable, or sufficient for the purpose....&dquo; To speak of teacher competencies, then, it is necessary to speak of purpose-competencies to accomplish goals. Before one can specify teacher competencies, he should first specify what effect he wishes the teacher to have on pupils. Said another way, what kinds of emotional, intellectual, social, and physical growth of pupils should the teacher facilitate? Once the desired consequences of teaching are determined, one can better identify those teaching competencies that are thought to facilitate such pupil growth. While this appears to be a simple statement of the obvious, its implications are anything but simple. When desired pupil outcomes are specified, how confident can one be of his ability to define teacher competencies which will in fact facilitate those outcomes? The assertion here is that the answer to this question is heavily dependent on the bases from which one chooses to generate statements of teacher competencies. Four different bases are explored in this section of the paper: philosophical, empirical, subject matter, and practitioner. Philosophical BaseIf one uses a philosophical base to generate state-.ments of teacher competencies-and we believe one Ishould-the philosophical base must explicate assump--tions and values regarding the nature of man, the purpose of education, and the nature of learning and instruction. These assumptions are necessarily value statements which may have little or no empirical basis. They either have not been or cannot be proved emirically. They set parameters within which teaching ompetencies can be specified, for each must be conistent with these basic assumptions and values.A fully developed set of assumptions permits the pecification of desired pupil outcomes. Thus, the assumptions and the desired pupil outcomes allow for the conceptualization of the teacher's role. That is, given the program's assumptions about man and education and a set of specified pupil outcomes consistent with those assumptions, the role of teacher can be conceptualized.Once the role of the teacher has been conceptualized, it is possible to generate statements of teaching competencies from the conceptualized role. Using only a philosophical base, the validity test for these competencies lies in their degree of consistency with the conceptualized role, the desired pupil outcomes, and the assumption statements.It may be helpful to illustrate this process with an example. T...

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