On structural equation modeling with data that are not missing completely at random

A general latent variable model is given which includes the specification of a missing data mechanism. This framework allows for an elucidating discussion of existing general multivariate theory bearing on maximum likelihood estimation with missing data. Here, missing completely at random is not a prerequisite for unbiased estimation in large samples, as when using the traditional listwise or pairwise present data approaches. The theory is connected with old and new results in the area of selection and factorial invariance. It is pointed out that in many applications, maximum likelihood estimation with missing data may be carried out by existing structural equation modeling software, such as LISREL and LISCOMP. Several sets of artifical data are generated within the general model framework. The proposed estimator is compared to the two traditional ones and found superior.The research of the first author was supported by grant No. SES-8312583 from the National Science Foundation and by a Spencer Foundation grant. We wish to thank Chuen-Rong Chan for drawing the path diagram.     

Hypertonic central nervous system complications from the viewpoint of the pathologist

Based on 2130 autopsies with a hypertension it is reported on the hypertensive CNS-lesions. The frequency of encephalomalacia was 12%. By 9.7% was founded brain haemorrhages. The relapse rate of haemorrhages was about 5%. The encephalomalacia existed by way of secondary finding in 24.7%, and the haemorrhage in 2.2%. The investigations showed an important arteriosclerosis by 39.8% in haemorrhages and by 51.6% in brain infarct. It was remarkable by the hypertensive brain haemorrhages a dominant right hemisphere.     

Ulnar sulcus syndrome--a contribution to course and prognosis

Of 1028 patients with 1138 peripheral nerve lesions, 142 suffered from an electrophysiologically proven SUS. At follow-up, 93 patients could be restudied. Spontaneous regressions were observed in patients below the age of 40 years and in case of a history under 6 months. So-called late pareses receded in no case without operative displacement of the ulnar nerve. However, if the etiology is unknown, the present results of investigation require reserve towards operative therapy.     

Occupational therapy in neurology--report of experiences from a university clinic

Starting from particularities in rehabilitation of neurological patients and by means of special criterions, the authors report on their own experiences in organizing occupational therapy in the neurologic department of a Medical Academy. Beside the requisite of a "therapy maintaining and restoring function", problems of resistance to stress and condition of the patient play a substantial part. Operational therapy within the group-specific situation provides necessary social communication to the neurologic patient, too.     

Validity of post-proline splitting dipeptidyl aminopeptidase activities in the cerebrospinal fluid for neurologic and psychiatric diagnosis

The dipeptidyl-peptidase activity of 650 liquores cerebrospinalis was obtained by means of the substrate Gly-Pro-NHNp (Gly-Pro-4-nitroanilid) at pHs of 5.5 and 7.4. In comparison with a reference collective, the suitability of the method as a supplementary liquor parameter in neurological psychiatric diagnosis was examined. The introduction of the measurement at pH 7.4 can be particularly recommended for the distinguishing of bacterial and nonbacterial meningitis.     

Maps between some different kinds of contraction function: The finite case

In some recent papers, the authors and Peter Gärdenfors have defined and studied two different kinds of formal operation, conceived as possible representations of the intuitive process of contracting a theory to eliminate a proposition. These are partial meet contraction (including as limiting cases full meet contraction and maxichoice contraction) and safe contraction. It is known, via the representation theorem for the former, that every safe contraction operation over a theory is a partial meet contraction over that theory. The purpose of the present paper is to study the relationship more finely, by seeking an explicit map between the component orderings involved in each of the two kinds of contraction. It is shown that at least in the finite case a suitable map exists, with the consequence that the relational, transitively relational, and antisymmetrically relational partial meet contraction functions form identifiable subclasses of the safe contraction functions, over any theory finite modulo logical equivalence. In the process of constructing the map, as the composition of four simple transformations, mediating notions of bottom and top contraction are introduced. The study of the infinite case remains open.     

Foundations of a new system of probability theory

The aim of my book is to explain the content of the different notions of probability.Based on a concept of logical probability, which is modified as compared with Carnap, we succeed by means of the mathematical results of de Finetti in defining the concept of statistical probability.The starting point is the fundamental concept that certain phenomena are of the same kind, that certain occurrences can be repeated, that certain experiments are identical. We introduce for this idea the notion: concept K of similarity. From concept K of similarity we derive logically some probability-theoretic conclusions:If the events E() are similar —of the same kind - on the basis of such a concept K, it holds good that intersections of n of these events are equiprobable on the basis of K; in formulae: E(₁)...E( _{n K} E('₁)...E(' _n , _{i j} ,' _j ' _j for ij On the basis of some further axioms a partial comparative probability structure results from K, which forms the starting point of our further investigations and which we call logical probability on the basis of K.We investigate a metrisation of this partial comparative structure, i.e. normed -additive functions m _K, which are compatible with this structure; we call these functions m _K measure-functions in relation to K.The measure-functions may be interpreted as subjective probabilities of individuals, who accept the concept K.Now it holds good: For each measure-function there exists with measure one the limit of relative frequencies in a sequence of the E().In such an event, where all measure-functions coincide, we speak of a quantitative logical probability, which is the common measure of this event. In formulae we have: l _K (h _n lim h _n )=1 in words: There is the quantitative logical probability one that the limit of the relative frequencies exists. Another way of saying this is that the event ^* (h_n lim h _n) is a maximal element in the comparative structure resulting from K.Therefore we are entitled to introduce this limit and call it statistical probability P.With the aid of the measure-functions it is possible to calculate the velocity of this convergence. The analog of the Bernoulli inequation holds true: m _K (¦h _n –P¦)1–1/4n².It is further possible in the work to obtain relationships for the concept of statistical independence which are expressed in terms of the comparative probability.The theory has a special significance for quantum mechanics: The similarity of the phenomena in the domain of quantum mechanics explains the statistical behaviour of the phenomena.The usual mathematical statistics are explained in my book. But it seems more expedient on the basis of this new theory to use besides the notion of statistical probability also the notion of logical probability; the notion of subjective probability has only a heuristic function in my system.The following dualism is to be noted: The statistical behaviour of similar phenomena may be described on the one hand according to the model of the classical probability theory by means of a figure called statistical probability, on the other hand we may express all formulae by means of a function, called statistical probability function. This function is defined as the limit of the relative frequencies depending on the respective state of the universe. The statistical probability function is the primary notion, the notion of statistical probability is derived from it; it is defined as the value of the statistical probability function for the true unknown state of the universe.As far as the Hume problem, the problem of inductive inference, is concerned, the book seems to give an example of how to solve it.The developed notions such as concept, measure-function, logical probability, etc. seem to be important beyond the concept of similarity.The present work represents a summary of my book Grundzüge zu einem neuen Aufbau der Wahrscheinlich-keitstheorie [5], For this reason, I have frequently dispensed with providing proof and in this connection refer the interested reader to my book.     

Altering information to gain action control: Functional aspects of human information processing in decision making

In recent approaches to social judgment, information distortion has been discussed primarily as a violation of individual rationality, due to unintentionally occurring biases. In contrast to this view, it is argued that frequently individuals make purposive use of selective changes in information processing in order to avoid indecisiveness. In this sense, selective changes in information processing may be considered a functional requirement of a volitional process which protects the current intention (or tentative decision) from being replaced by competing behavioral tendencies. On the basis of J. Kuhl's theory of action control (1981, Journal of Personality and Social Psychology, 40, 155–170; 1982, in W. Hacker, W. Volpert, & M. von Cranach, Eds., Cognitive and Motivational Aspects of Action, Amsterdam: North-Holland, 1984, in B. A. Maher, Progress in Experimental Personality Research, Vol. 13, New York: Academic Press) it was predicted that subjects having a high score on the action-control scale (i.e., action-oriented subjects) should show a stronger tendency to increase the attractiveness rating of a tentatively preferred decision during the process of decision making than subjects scoring low on that scale (i.e., state-oriented subjects). To test this assumption, students searching for an apartment were offered 16 apartments along with a list containing information about the alternatives. The subjects had to rate the attractiveness of each apartment twice before they were asked to indicate which apartments they would like to rent. The results confirmed the predictions. It was found that action-oriented subjects increased the divergence of their attractiveness ratings from the first to the second point of evaluation, whereas state-oriented subjects did not.     

Determination of dipeptidyl aminopeptidase activities in the cerebrospinal fluid

The investigation of enzyme activity in cerebrospinal fluid has been without relevant results for laboratories analysing spinal fluid. For neurochemical purposes, it is interesting that the Substance P is convered by Depeptidyl-aminopeptidase IV (DP IV), liberating dipeptides. The hydrolysis of nitroanilids of the form Xaa-Pro-NHNp in cerebrospinal fluid was analysed using them as peptidases substrates. Finally a method for measuring the activity was proposed.