APL functions for interactive data analysis: Principal components analysis

APL functions to support principal components analysis are presented: a general-purpose function to obtain eigen values and eigen vectors, a more specialized function to convert these into the results commonly given by principal components analysis, and a user interface function that accesses filed data, offers flexibility in data selection, and produces labeled output. A brief introduction to the logic and uses of principal components analysis is included. General-purpose support functions to simplify file use and to increase the range of options available to the user are also provided.     

APL functions for interactive data analysis: Graphics and labels

APL functions designed to provide labeled plots and histograms are described. Support functions that augment a data file with necessary information to label output and to maintain a common plotting scale are also described. APL code and illustrative output are presented.     

An APL system for interactive data analysis: Histograms,correlation, and regression

This report describes an APL system for file-oriented univariate analysis, correlation, and regression analysis. The correlation and regression processes permit analyses of an unlimited number of cases, if the cases are arranged in tables small enough to be processed one at a time in a workspace. Support functions are also given for a menu-based processing system designed to support a broad range of analyses. The functions offer features such as subset selection, data transformation, and exclusion of invalid items.     

Statistical modelling of network panel data: goodness of fit

Networks of relationships between individuals influence individual and collective outcomes and are therefore of interest in social psychology, sociology, the health sciences, and other fields. We consider network panel data, a common form of longitudinal network data. In the framework of estimating functions, which includes the method of moments as well as the method of maximum likelihood, we propose score-type tests. The score-type tests share with other score-type tests, including the classic goodness-of-fit test of Pearson, the property that the score-type tests are based on comparing the observed value of a function of the data to values predicted by a model. The score-type tests are most useful in forward model selection and as tests of homogeneity assumptions, and possess substantial computational advantages. We derive one-step estimators which are useful as starting values of parameters in forward model selection and therefore complement the usefulness of the score-type tests. The finite-sample behaviour of the score-type tests is studied by Monte Carlo simulation and compared to t-type tests.     

The function debate: between “cheap tricks” and evolutionary neutrality

We examine the use of the notion of natural selection in the philosophical debate on functions in biology. This debate has been largely shaped by the way in which different accounts assess various selective pressures in justifying claims about biological functions. Cummins (Functions: new essays in the philosophy of psychology and biology. Oxford University Press, Oxford, pp 157–172, 2002), one of the main proponents of the causal role account of biological functions, argues that a correctly understood neo-Darwinian notion of natural selection has nothing to do with functional talk in biology. In this paper, we counter Cummins’ account by showing that progress in the molecular approaches to evolutionary biology—specifically scientific data available in neo-functionalization research—offers valuable support to the etiological selectionist approach to functions in biological and biologically-related sciences. Finally, we use the presented data to build our own account of biological functions, which tries to avoid the wrong turns taken by both major strands in the biological function debate, namely causal role and etiological accounts. According to our account, the function of a certain gene or a protein in the biological system that contains it is a particular causal activity, or a group of causal activities whose manifestation is in a specific way determined by corresponding mechanisms of genetic expression. Also, we argue that in many important cases this particular expression of genetic activity was positively selected at a certain point in evolutionary history. Since we take selection as an important but not the only factor that grounds biological functions, we are committed to a weak etiological account.     

An incomplete data approach to the analysis of covariance structures

In this paper, linear structural equation models with latent variables are considered. It is shown how many common models arise from incomplete observation of a relatively simple system. Subclasses of models with conditional independence interpretations are also discussed. Using an incomplete data point of view, the relationships between the incomplete and complete data likelihoods, assuming normality, are highlighted. For computing maximum likelihood estimates, the EM algorithm and alternatives are surveyed. For the alternative algorithms, simplified expressions for computing function values and derivatives are given. Likelihood ratio tests based on complete and incomplete data are related, and an example on using their relationship to improve the fit of a model is given.This research forms part of the author's doctoral thesis and was supported by a Commonwealth Postgraduate Research Award. The author also wishes to acknowledge the support of CSIRO during the preparation of this paper and the referees' comments which led to substantial improvements.     

Selection-based virtual keyboard prototypes and data collection application

An emerging area of research in engineering psychology is the evaluation of text entry for mobile devices using a small number of keys for the control of cursor direction and character selection from a matrix of characters (i.e., selection-based data entry). The present article describes a software tool designed to reduce time and effort in the development of prototypes of alternative selection-based text-entry schemes and their empirical evaluation. The tool, available for distribution to researchers, educators, and students, uses Action Script code compiled into an executable file that has an embedded Adobe Flash Player and is compatible with most operating systems (including Microsoft Windows, Apple OSX, and Linux).     

Data acquisition software for high data rate experiments

A computerized perceptual laboratory operates a variety of stimulus devices, including static and dynamic graphics displays, and records both discrete and analog data in a diverse and complex set of experimental paradigms. The software requirement to accommodate this variety of paradigms and high input and output data rates has been met by a single multitasked acquisition program that interprets unitary event commands to display graphics or nongraphics stimuli, record responses, control timing, or provide appropriate feedback. Event lists are created and modified with a text editor, then assembled into binary experiment definition files by dialogue with a parsing program. Graphics stimuli are referenced by a file name that contains stimulus attributes for later data extraction. All protocols and stimulus files are loaded prior to the block of trials, so no disk accesses that would delay events are required during a block. The resulting data file contains a record of all variable stimulus and timing information, as well as the discrete and analog responses, in a uniform format which facilitates data extraction.     

The effect of smoothing functions on data obtained from a FFT

This research investigated the effect on power spectra when data-smoothing functions were used on EEG data prior to submitting them to a FFT. We used two smoothing function options: not using any smoothing function and using the Parzen smoothing function. We developed a program to evaluate each of these functions with real and standard data. When a set of data is submitted to smoothing prior to being submitted to a FFT, there are statistically significant differences in the power spectra obtained from the FFT. This finding holds true for standard waveforms as well as for real EEG data.     

Automated data collection using bar code

Using bar code technology to automate data collection provides a rapid and reliable alternative to paper-and-pencil tracking or keyboard entry into pocket or laptop computer. An array of bar code symbols is printed on a data menu, with a unique symbol corresponding to each possible observation. Bar code symbols are scanned using hand-held readers, which record the event, log the observation time, and store data for transfer to a personal computer. Advantages of the bar code monitoring system include: (1) ease of use by staff with minimal technical training, (2) reduced data entry errors and increased entry speed, (3) reliable portable operation, and (4) low-cost hardware. While the bar code system described here is used for behavioral monitoring in a residential treatment setting for the developmentally disabled, with minimal modification this system can be adapted for use in a wide variety of research and clinical applications.     

The Observer Video-Pro: New software for the collection, management, and presentation of time-structured data from videotapes and digital media files

The Observer Video-Pro is a system for collecting, managing, analyzing, and presenting observational data. It integrates The Observer software with time code and multimedia hardware components. It extends the functionality of a conventional real-time event recording program in various ways. Observational data can be collected, reviewed, and edited with synchronized display of the corresponding video images. For optimal visual feedback during coding, one can display the video image in a window on the computer screen. Video playback from either a VCR or a digital media file can be controlled by the computer, allowing software-controlled jog, shuttle, and search functions. Besides a wide range of VCRs, The Observer Video-Pro supports all major digital video file formats. The software allows the user to summarize research findings in numerical, graphical, or multimedia format. One can create a time-event plot for a quick glance at the temporal structure of the observed process, or run specific analysis procedures and generate reports with statistics. An Event Summary function is available for exploratory and qualitative analysis. Video material can be summarized in a Video Play List, which allows on-screen summary presentations or the creation of highlight compilations on tape, CD, or other media. Video images can be captured and saved as disk files, for use as illustrations in documents, slides for presentations, and so forth. In this paper we describe the design and operation of the system, illustrated with a case study from research on Repetitive Strain Injury (RSI).     

PROMPTING ONE LOW-FAT,HIGH-FIBER SELECTION IN A FAST-FOOD RESTAURANT

Evidence increasingly links a high-fat, low-fiber diet to coronary heart disease and certain site cancers, indicating a need for large-scale dietary change. Studies showing the effectiveness of particular procedures in specific settings are important at this point. The present study, using an A-B-A-B design and sales data from computerized cash registers, replicated and extended previous work by showing that inexpensive prompts (i.e., signs and fliers) in a national fast-food restaurant could increase the sales of salads, a low-fat, high-fiber menu selection. Suggestions also are made pertinent to more widespread use of the procedures.     

Component processes of phased decision strategies

It is often assumed that decision makers apply mixtures of strategies including heuristic processes in complex choice tasks. In support of this assumption the component processes involved in phased strategies were investigated. Expectations for an experimental investigation were generated by simulations within the effort-quality framework. Effort-quality trade-off functions for tasks of different complexity favor compensatory dimension-based strategies for binary choice. For multialternative choice, a combination of initial dimension-based elimination procedures followed by alternative-based final processing would be expected. These expectations were tested in two experiments. While choosing between two, four, or eight alternatives, subjects could successively retrieve parts of the available information. Depending on their menu selection, either all features of one alternative were displayed together (alternative-based retrieval), or all features on one dimension were displayed together (dimension-based retrieval). Vincent averaging was used to analyze the retrieval sequences with respect to their stationarity. While the stationary sequences for binary choice are compatible with single processing strategies, non-stationarity of the sequences obtained for multialternative choice indicates the use of phased strategies. In particular, non-stationarity due to decreasing dimension-based retrievals over time suggests that subjects first applied dimensional elimination and later derived their choices by more thorough, alternative-based processing of the remaining alternatives.     

ODAP: a stand-alone program for observational data acquisition

A software program written to collect real-time, observational data is described. The flexible program allows customized behavior codes and observational durations and simultaneously records both timed and counted events. The data are collected by means of single keystrokes, automatically stored to disk with 100th of a second resolution and summarized for each observational session. The program’s database files are dBASE III PLUS compatible and may be browsed, edited, or converted to ASCII files from the program’s main menu. Field testing demonstrated the efficiency and interobserver reliability of the program (for frequency,r=0.81; for durational behaviors,rs=0.89 and 0.96). The software operates on IBM XT/AT/PS 2s and most clones with PC/MS DOS version 2.0 or greater.     

MacLaboratory Controller: A switch and A/D interface between Apple’s Macintosh and peripheral apparatus

Apple’s Macintosh microcomputer has advantages over other systems used for laboratory control and data acquisition, especially because of its graphic and user-friendly features. However, a major perceived limitation has been its closed architecture. We describe an interface using the RS 422 modem port that supports up to 64 input/output (I/O) functions including analog-to-digital 4–12 channel input. The Controller software supplies an easily edited authoring tool in which functional relationships, logical operators, timing (millisecond accuracy), and counting functions are established through simple mouse and menu commands. Data from I/O functions may be displayed or saved as tab-delimited files that can be opened by various Macintosh statistical and spreadsheet packages and that are transportable to some mainframe applications.     

Charting the process of change: A primer on survival analysis

Survival analysis is a powerful and useful technique for understanding qualitative change. This article provides a practical, nontechnical introduction to the use of survival analysis for social scientists. Important issues in using survival analysis are discussed, including research design, data preparation and management, and data analysis. Attendance data from a self-helf organization are used to illustrate common survival analysis tasks such as describing the overall survival and hazard functions, examining covariate effects, and modeling the form of the hazard function over time. An appendix that discusses the strengths and weaknesses of current survival analysis computer programs is included. Editor's note: Edward Seidman served as action editor for this article while serving as Associate Editor for Methodology.I thank William Davidson, Susan Englund, Bruce Rapkin, Kurt Ribisl, and three anonymous reviewers for their helpful comments on earlier drafts. The example data presented here were collected with the support of an NIMH grant (MH37390) awarded to Julian Rappaport and Ed Seidman.     

初级运动区的fMRI实验研究

本实验采用功能磁共振为实验仪器,被试进行运动准备和运动执行两种作业活动,实验设计为延时序列运动任务。在对实验数据进行预处理,反卷积、标准化处理后,采用欧式距离公式进行聚类统计,统计结果显示,M1区不仅具有运动执行和运动准备的功能,还发现其他功能区域的激活,不是单纯的运动执行功能,这一区域与三种活动有关。     

A quantitative model of optimal data selection in Wason's selection task.

The optimal data selection model proposed by Oaksford and Chater (1994) successfully formalized Wason's selection task (Wason, 1966). The model, however, involved some questionable assumptions and was also not sufficient as a model of the task because it could not provide quantitative predictions of the card selection frequencies. In this paper, the model was revised to provide quantitative fits to the data. The model can predict the selection frequencies of cards based on a selection tendency function (STF), or conversely, it enables the estimation of subjective probabilities from data. Past experimental data were first re-analysed based on the model. In Experiment 1, the superiority of the revised model was shown. However, when the relationship between antecedent and consequent was forced to deviate from the biconditional form, the model was not supported. In Experiment 2, it was shown that sufficient emphasis on probabilistic information can affect participants' performance. A detailed experimental method to sort participants by probabilistic strategies was introduced. Here, the model was supported by a subgroup of participants who used the probabilistic strategy. Finally, the results were discussed from the viewpoint of adaptive rationality.