Factor analysis by generalized least squares

Aitken's generalized least squares (GLS) principle, with the inverse of the observed variance-covariance matrix as a weight matrix, is applied to estimate the factor analysis model in the exploratory (unrestricted) case. It is shown that the GLS estimates are seale free and asymptotically efficient. The estimates are computed by a rapidly converging Newton-Raphson procedure. A new technique is used to deal with Heywood cases effectively.The work on this project was done when the first author was Research Statistician at Educational Testing Service, Princeton, N. J. The second author was in part supported by a grant from the Research Committee of the University of Wisconsin Graduate School. The authors wish to thank Michael Browne for many helpful comments and Marielle van Thillo for valuable assistance in the numerical computations.     

An individual difference model for the multidimensional analysis of preference data

A model for the analysis of paired comparison data is presented which combines features of the BTL-model with features of the Unfolding model. The model is metric, mathematically tractable, and has an exact algebraic solution. Since it is multidimensional and allows for individual differences, it is thought to be more realistic for some choice situations than either the Thurstone model or the BTL-model. No claim is made that the present model will be appropriate for all conceivable choice situations. Rather, it is argued that the fact that it is explicitly falsifiable is a point in its favor.This work was supported by a grant of the United States Public Health Service (1 R03 MH19139 01 MSM) and a David Ross (XR) grant of the Purdue Research Foundation (PRF 2132), both of which are gratefully acknowledged. We also owe thanks to Dr. Terry Cooper, whose careful scrutiny of an earlier draft of this paper allowed us to reduce the number of errors from n to n-1.     

Some new results on factor indeterminacy

Some relations between maximum likelihood factor analysis and factor indeterminacy are discussed. Bounds are derived for the minimum average correlation between equivalent sets of correlated factors which depend on the latent roots of the factor intercorrelation matrix . Empirical examples are presented to illustrate some of the theory and indicate the extent to which it can be expected to be relevant in practice.     

Negation of Park's transformations

Zusammenfassung Parks Kritik beruht, meiner Ansicht nach, auf einem entscheidenden Mißverständnis meiner Intentionen: es geht mir überhaupt nicht um eine Argumentation gegen eine Transformationsgrammatik à la Chomsky, und nicht einmal in erster Linie gegen die Absicht mancher Psycholinguisten, eine derartige Theorie in ihren psychischen Funktionen aufzuzeigen. Ich möchte lediglich dafür plädieren, daß die Psycholinguistik in erster Linie psychologische (und nicht linguistische) Überlegungen und Modellvorstellungen als Leitlinien verwendet.     

Pause measures during reading and recall in serial list learning

An investigation is reported into pausing and grouping during the serial learning of letter strings, when presented randomly by length and when presented in ascending order. Mean pause times for the reading and recall of longer lists were significantly greater than for lists of shorter span due to extended pausing at specific list positions. In general, reading rhythms were duplicated during recall. Subjects were highly consistent in maintaining their level of pause duration across lists and responded to additions in list length by increasing their number of groups, not by increasing group size. Triadic sequences were the most popular form of spontaneous organization. Pausing measures are discussed as indices of organizational strategies.     

Auditory evoked brain responses: Intensity functions from bipolar human scalp recordings

Average evoked brain responses were computed from four simultaneous recordings during binaural tone stimulation at 10 intensity levels. Amplitudes and latencies were measured for the prominent components, and linear regression coefficients were computed. The results indicate that the sensitivity of the evoked response to stimulus intensity is dependent upon the selection of the appropriate measure. Linear amplitude functions were demonstrated. Additional research relating these responses to psychophysical measures is suggested.     

Detection of extraneous signals during sentence recognition

In two separate experiments, 40 Ss were presented with recorded sentences during each of which a click occurred. Ss had to depress a key as soon as they heard the click. RTs were f aster when the click was located at the major syntactic break of the sentence compared with RTs to clicks not at a break. This confirmed the hypothesis that processing load is a function of the surface structure of sentences, although the role of minor breaks was not clear. A second finding was that RTs were slower when the click was in the first rather than in the second half of the sentence. This can also be explained in terms of differential processing loads.