Comparison of "joint moderators" in three prediction techniques.

Examined the existence of 2 potential "joint moderator" variables (anxiety and study habits), and compared their operation according to 3 different prediction techniques: (a) subgroup analysis, (b) differential prediction of predictability, and (c) moderated regression. Results with 393 undergraduates indicate that anxiety moderated the relationship between GPA and American College Test scores using subgroup analysis and differential predictability techniques. A comparison of moderated regression with linear regression indicated that study habits operated as an independent predictor. None of the techniques identified joint moderators in this situation. Results are discussed in the light of problems and assumptions of each technique. The need for systematic identification of moderators from a large mass of data is indicated. (17 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A new binderless thick-film piezoelectric paste

This paper presents an investigation into a screen printable piezoelectric paste formulated from a blend of PZT-Pz29 powders of different mean particle size mixed in an organic vehicle. In order to enhance d₃₃ properties of the thick-film (a piezoelectric coefficient), no binder material was mixed into the paste. The d₃₃ coefficient and maximum applied electrical field of devices processed at peak temperatures of 150, 200, 750, 850 and 1,000°C were measured and the film adhesion assessed using scratch and tape tests. The applications that would benefit from these enhanced properties are also discussed. The thick-films produced at these processing temperatures showed good adhesion to 96% alumina substrates. They also showed the ability to withstand high electrical fields and a significant enhancement in d₃₃ when compared to thick-film materials processed at similar temperatures using polymer or glass binders. A maximum average d₃₃ value of 168pCN⁻¹ was obtained for samples processed at a peak temperature of 1,000°C. This is 28% higher than the reported d₃₃ value for a conventional piezoelectric thick-film processed at the same temperature. All samples withstood electric field strengths of over 14 MVm⁻¹ which is between 2.5 and 4.5 times higher than that used for conventional piezoelectric thick-films.     

Importance ratings in job analysis: Note on the misinterpretation of factor analyses.

A common practice in job analysis involves having subject matter experts (SMEs) provide importance weights for the behaviors identified as characteristics of a given job, and then grouping those behaviors by factor analysis. Two problems with using factor analysis on these data are explored: (a) The factors that emerge from such an analysis are not interpretable as important dimensions of the job, and (b) job dimensions that SMEs agree are important will not emerge as factors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A recomparison of behavioral expectation scales to summated scales.

Compared behavioral expectation scales (BES) to summated scales for leniency error, discriminability (among ratees), interrater agreement, and constancy of rater individual differences across dimensions. 27 university instructors were rated by their students. Less leniency error and greater interrater agreement were found for item-analyzed, summated scales. Results are discussed in terms of previous comparisons of the 2 methods and possible effects of variant developmental procedures on BES performance. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Novel Thick-Film Piezoelectric Slip Sensor for a Prosthetic Hand

The ability to mimic the tactile feedback exhibited by the human hand in an artificial limb is considered advantageous in the automatic control of new multifunctional prosthetic hands. The role of a slip sensor in this tactile feedback is to detect object slip and thus provide information to a controller, which automatically adjusts the grip force applied to a held object to prevent it from falling. This system reduces the cognitive load experienced by the user by not having to visually assess the stability of an object, as well as giving them the confidence not to apply unnecessarily excessive grip forces. A candidate for such a sensor is a thick-film piezoelectric sensor. The method of fabricating a thick-film piezoelectric slip sensor on a prototype fingertip is described. The construction of experimental apparatus to mimic slip has been designed and analyzed to allow the coefficient of friction between the fingertip and the material in contact with the fingertip to be calculated. Finally, results show that for a coefficient of friction between the fingertip and grade P100 sandpaper of approximately 0.3, an object velocity of 0.025plusmn0.008 ms^-1 was reached before a slip signal from the piezoelectric sensor was able to be used to detect slip. It is anticipated that this limiting velocity will be lowered (improved) in the intended application where the sensor electronics will be powered from a battery, connections will be appropriately screened, and if necessary a filter employed. This will remove mains interference and reduce other extraneous noise sources with the consequence of an improved signal-to-noise ratio, allowing lower threshold values to be used in the detection software     

A note on concurrent and predictive validity designs: A critical reanalysis.

Comments on an article in which G. Barrett et al (see record 1981-11631-001) argued that the conceptual distinction between predictive and concurrent validity has been exaggerated. The present authors offer a more complete classification of validity designs and illustrate sources of differences in the quality of the validity estimates obtained. Five kinds of predictive designs for selection research are identified: (a) follow-up with random selection, (b) follow-up with selection by existing systems, (c) selection based on test to be validated, (d) selection preceding testing, and (e) shelf research. For some of these, and for corresponding concurrent designs, problems arise from the lack of data for informed estimates of appropriate population parameters. It is pointed out that severe range restriction intensifies parameter estimation and the risk of Type II error. Corrections suggested for the effects of contaminations such as age, tenure, and experience are shown to be oversimplifications. It is concluded that on both conceptual and practical bases different validity designs are not equivalent or interchangeable. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)