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PubMed1998

Brain is related to behavior (p<.05).

This article demonstrates that sole reliance on tests of statistical significance in the analysis and interpretation of neuropsychological data that is grounded in quasi-experimentation can systematically confound the conclusions drawn from our neuropsychological research regarding brain-behavior relations. The conclusion of this article is that we must accompany the statistical significance test with more appropriate statistics--namely, point-estimate effect sizes along with interval estimation and meta-analysis for the analysis of data from multiple studies. The argument for this conclusion is demonstrated from the re-analysis of published neuropsychological test findings. It is recommended on the basis of this review that the consumer of neuropsychological reports will be better served if due consideration is given to the magnitude of effect in brain-behavior statistical analyses.

Data Interpretation, Statistical↗
PubMedDate not supplied

Publications from multicentre clinical trials: statistical techniques and accessibility to the reader.

Articles from multicentre randomized clinical trials were analysed by methods adapted from Emerson and Colditz and Juzych et al. to compare the frequency with which different statistical methods are used by clinical trials investigators with the frequency used by other researchers, and to determine how much statistical knowledge is required to interpret the statistical treatment of data from clinical trials. We observed differences between the frequency of usage of statistical methods and the accessibility of the clinical trials publications and those of all medical research articles published by specific journals. Clinical trials publications are less accessible than others in medical journals to the reader who knows only descriptive statistics, t-tests, contingency tables, power calculations, and life table methods. Many more statistical methods must be known by a reader to understand fully publications regarding treatment group comparisons for the primary outcomes of interest from clinical trials.

Data Interpretation, Statistical↗
PubMed2005

BADASP: predicting functional specificity in protein families using ancestral sequences.

SUMMARY: Burst After Duplication with Ancestral Sequence Predictions (BADASP) is a software package for identifying sites that may confer subfamily-specific biological functions in protein families following functional divergence of duplicated proteins. A given protein phylogeny is grouped into subfamilies based on orthology/paralogy relationships and/or user definitions. Ancestral sequences are then predicted from the sequence alignment and the functional specificity is calculated using variants of the Burst After Duplication method, which tests for radical amino acid substitutions following gene duplications that are subsequently conserved. Statistics are output along with subfamily groupings and ancestral sequences for an easy analysis with other packages. AVAILABILITY: BADASP is freely available from http://www.bioinformatics.rcsi.ie/~redwards/badasp/

Algorithms↗
PubMed1988

Frequency distribution histograms for the rapid analysis of data.

The mean and standard error are good representations for the response of a population to an experimental parameter and are frequently used for this purpose. Frequency distribution histograms show, in addition, responses of individuals in the population. Both the statistics and a visual display of the distribution of the responses can be obtained easily using a microcomputer and available programs. The type of distribution shown by the histogram may suggest different mechanisms to be tested.

Biometry↗
PubMed1995

When you can't ask their names: linking anonymous respondents with the Hogben number.

This article describes a method of linking anonymous subjects with a respondent-generated code using an algorithm based on personal details to produce unique identifiers. It was used to increase confidentiality and statistical power in a year-long work-place health promotion evaluation. Subjects were employees of a large retail chain; 80 per cent were female, and the majority educated to high school level. Of the 385 possible, 81 per cent matched; 67 per cent of the codes were matched on all elements and another 14 per cent were accepted as 'fuzzy' matches. Linking respondents increased the statistical power of the study from an unacceptable 0.4 to an acceptable 0.8. Other research on linking records is briefly discussed, including sample bias and probabilistic matching. This technique is useful when anonymity is likely to raise response rates, but the ideal code could be further sought.

Adult↗
PubMed1990

Graphical display and statistical evaluation of data gained by long-term ambulatory intragastric pH monitoring.

The graphical display of data gained by long-term ambulatory intragastric pH monitoring requires different methods to present (1) the circadian time course of each individual, (2) data from all individuals belonging to the same group, and (3) data from two or more groups in a summary plot. Data reduction is normally required in all three cases; for this purpose, it is advisable to use median values from consecutive time periods, e.g. of 10-20 min each. All data from a total group of comparable individuals may be displayed using a pseudo-3D-graph allowing for easy recognition of interindividual variability. Summary curves from all data of one group may be gained by calculating medians from time-equivalent pH values and plotted together in one graph. The study design should take into consideration that intraindividual reproducibility of intragastric pH metry is excellent, while large variations may occur between individuals. Therefore, repeated measurements in the same individual under the different conditions to be tested are highly recommended. If two measurements are performed in each individual, the data are statistically evaluated using Wilcoxon paired rank test; Friedman rank test and subsequent multiple comparison according to Wilcoxon-Wilcox are proposed in the case of more than two groups. Alternatively, multiple single tests may be used; this procedure, however, requires appropriate correction of the alpha-error which is best done using the exact versions of the test.

Circadian Rhythm↗
PubMed2002

Modelling the state of bone cysts by statistical analysis of intensities of x-ray images.

The subject of this article is the state of a benign bone disease. The principle aim of this study is the construction of a statistical model for estimating the otherwise unobservable variable for the state of the disease. The distribution of intensity of X-ray images of the affected part and the healthy part of the bone are evaluated. Quantiles of both distributions are used in the estimation of a multinomial logit model by which the variable for the state of the disease is quantified.

Bone Cysts↗
PubMed2003

Autocorrelation problems in short time series.

The work of Huitema (1985) on autocorrelation in behavioral data suggests that the use of conventional statistical methods is justified. The present study restates the problem of autocorrelation by analyzing 100 baselines of small samples designs published in the Journal of Applied Behavior Analysis during 1992. The results show a negative bias in the autocorrelations, especially with very small samples. The autocorrelation values are normally distributed, and the method of Davies, Trigg, and Newbold (1977) is the most accurate in calculating the standard deviation.

Data Interpretation, Statistical↗
PubMed2001

Aggregate time-series regression in the field of alcohol.

Time-series regression of successive aggregate data has been used widely to explore relationships between substance use and harm, or to measure effects of policy interventions. This paper suggests minimal standards to conduct such analyses with respect to validity and reliability of underlying data, statistical techniques and requirements and interpretation of results.

Alcohol Drinking↗
PubMedDate not supplied

Microcomputer-based system to measure, record and process flow-volume curves, respiratory questionnaire data and environmental exposure.

A microcomputer-based system was developed to measure flow-volume curve parameters, record respiratory questionnaire data and analyse the collected data. The hardware of the system consists of two parts which operate independently and are linked together for data transfer. The first part is a microprocessor-based unit to accurately measure flow-volume curve parameters. The second part is a microcomputer unit used to receive flow-volume curve parameters from the first part, to record responses to questionnaires stored in the unit and to perform all statistical analysis. The software included a monitor program controlling system operations, a data base and a powerful statistical package. Two sets of questionnaires are stored in the system, one for adults and the other for children. The user is only required to enter to the system answers to questions displayed on the screen. Flow-volume data can be entered via the keyboard of the microcomputer unit or transmitted from the flow-volume test unit. The developed system is compact, easy to operate and moderately priced.

Adult↗
PubMed2000

Statistical inference on associated fertility life table parameters using jackknife technique: computational aspects.

Knowledge of population growth potential is crucial for studying population dynamics and for establishing management tactics for pest control. Estimation of population growth can be achieved with fertility life tables because they synthesize data on reproduction and mortality of a population. The five main parameters associated with a fertility life table are as follows: (1) the net reproductive rate (Ro), (2) the intrinsic rate of increase (rm), 3) the mean generation time (T), (4) the doubling time (Dt), and (5) the finite rate of increase (lambda). Jackknife and bootstrap techniques are used to calculate the variance of the rm estimate, which can be extended to the other parameters of life tables. Those methods are computer-intensive, their application requires the development of efficient algorithms, and their implementation is based on a programming language that encompasses quickness and reliability. The objectives of this article are to discuss statistical and computational aspects related to estimation of life table parameters and to present a SAS program that uses jackknife to estimate parameters for fertility life tables. The SAS program presented here allows the calculation of confidence intervals for all estimated parameters, as well as provides one-sided and two-sided t-tests to perform pairwise or multiple comparison between groups, with their respective P values.

Animals↗
PubMed2001

Mutual information of population codes and distance measures in probability space.

We studied the mutual information between a stimulus and a system consisting of stochastic, statistically independent elements that respond to a stimulus. Using statistical mechanical methods the properties of the mutual information (MI) in the limit of a large system size N are calculated. For continuous valued stimuli, the MI increases logarithmically with N and is related to the log of the Fisher information of the system. For discrete stimuli the MI saturates exponentially with N. We find that the exponent of saturation of the MI is the Chernoff distance between response probabilities that are induced by different stimuli.

Brain↗
PubMed1989

A knowledge-based system for data analysis and interpretation.

Traditionally, statistical packages are employed to derive or infer facts about a Universe of Discourse through data analysis and interpretation. It is analysis that serves to transform data into information. Statistical packages provide the users with relatively easy-to-use and powerful mechanics of data analysis, but up to now they do not provide much help with the design and strategies of the analysis. As such, there is a risk of misuse of these packages by statistically inexperienced users. We propose the use of knowledge-based interfaces to support this category of users in statistical evaluations. This paper discusses our experiences from the implementation of a knowledge-based system called MAXITAB. It provides guidance in the processes of data analysis and interpretation and has been programmed as an interface to the statistical package MINITAB.

Data Interpretation, Statistical↗
PubMedDate not supplied

Computerized blood pressure and heart rate recording system interfaces standard chart recorder with any micro-computer.

The designed inexpensive blood pressure recording system (BPRS) gives any microcomputer direct on-line blood pressure and heart rate recording capability that will save research time and increase the accuracy of collected data. The data is automatically stored in a file compatible with most graphic and statistical processing software. In vitro testing, over a range of 0-200 mmHg and 0-360 beats per minute showed a 0.999 intraclass correlation. In vivo testing of the BPRS used anaesthetized rats whereby their systolic and diastolic pressures were measured simultaneously with heart rate. The blood pressures and heart rate data, measured by the BPRS demonstrated excellent stability, sensitivity and accuracy when compared to those measured by standard pressure transducers in conjunction with a Grass polygraph and a sphygmomanometer.

Animals↗
PubMed1996

Temporal and spatial analysis of potential maps via multiresolution decompositions.

Cardiac potentials recorded on the epicardium or the body surface by an array of electrodes are usually analyzed either as spatial distributions or temporal waveforms. Thus, the analysis often involves temporal descriptors (eg. max dV/dt) or spatial descriptors (eg. location of local extrema) only. The best known transform technique that has been applied to these data that combines both spatial and temporal characteristics is the Karhunen-Loeve transform, a global transform applied to temporal and/or spatial bases obtained by statistical analysis of a database. As an alternative, multiresolution decompositions and related wavelet-type transforms have recently seen great development in signal processing and related fields. They offer flexibility, employing transformations onto local (rather than global) and fixed (rather than data-dependent) databases, and allow transformation of distributions, waveforms, or both, as desired. The utility of this method as applied to temporal and spatial segmentation and analysis of map data from both epicardial plaques and body surface potentials recorded during percutaneous transluminal coronary angioplasty is illustrated.

Body Surface Potential Mapping↗
PubMed2004

Stochastic reasoning, free energy, and information geometry.

Belief propagation (BP) is a universal method of stochastic reasoning. It gives exact inference for stochastic models with tree interactions and works surprisingly well even if the models have loopy interactions. Its performance has been analyzed separately in many fields, such as AI, statistical physics, information theory, and information geometry. This article gives a unified framework for understanding BP and related methods and summarizes the results obtained in many fields. In particular, BP and its variants, including tree reparameterization and concave-convex procedure, are reformulated with information-geometrical terms, and their relations to the free energy function are elucidated from an information-geometrical viewpoint. We then propose a family of new algorithms. The stabilities of the algorithms are analyzed, and methods to accelerate them are investigated.

Algorithms↗
PubMed2005

Significance testing, interval estimation or Bayesian inference: comments to "Extracting a maximum of useful information from statistical research data" by S. Sohlberg and G. Andersson.

Statistical inference plays an important part in the formation of scientific knowledge in psychology. Starting from a paper by Sohlberg and Andersson (2005; Scandinavian Journal of Psychology, 46, 69-77) these issues are discussed. It is argued that interval estimates are easy to understand and that they are more suitable than significance testing for most problems. Bayesian inference is a coherent description of the information building process. With some examples it is shown that null hypothesis significance testing is full of contradictions. Finally, some other important issues like convenience sampling and model selection are shortly mentioned.

Bayes Theorem↗
PubMed2001

A statistical interpretive method for neuropsychological test data.

The accurate interpretation of large numbers of neuropsychological tests within a flexible battery approach is a difficult and sometimes controversial process. We present a statistically based method of interpretation (Rohling's Interpretive Method or RIM) and evaluation of neuropsychological data that allows for varying numbers of tests along a varying number of cognitive domains, yet remains psychometrically based. This method requires informed clinical judgment in that the level of confidence for tests, cognitive domains, and global indices are used as the backdrop for interpretive decisions. Specific procedures for use are presented in a systematic, detailed fashion to allow the interested reader to replicate the method. Two case examples are presented: a straightforward case of cerebrovascular insult and a more complicated case of mixed etiology. Examples include a variety of different neuropsychological tests commonly used in a flexible battery approach. A discussion of the practicality, ease of use, and potential limitations of this method are further presented.

Data Interpretation, Statistical↗