Analysis Of Variance Design Research Articles

Age-Related Effects of Dichotic Attentional Mode on Interaural Asymmetry: An AERP Study with Independent Component Analysis.

The degree of interaural asymmetry (IA) obtained on a dichotic listening task is affected by attentional demands attributable to the mode of test administration. Previous research has shown that IA in the elderly is more influenced by increased attentional demands than young adults (YAs), but the effect of attentional mode on IA in middle-aged adults (MAs) has not been established. Auditory event-related potentials (AERPs), such as the N400, allow the evaluation of subtle differences in linguistic and cognitive processing between YAs and MAs that are imperceptible by behavioral means. To determine the effect of dichotic attentional mode on IA in the N400 in YA and MA listeners. Participants listened to groups of words that consisted of a reference word followed by dichotic probe words. Participants judged whether probe words were semantically related or unrelated to the reference word. This semantic judgment task was elicited in both divided-attention (DIV) and directed-attention (DIR) modes. Twenty-three YA (19-25 yr) and twenty-three MA (47-59 yr) females participated in the study. Individual, as well as grand-averaged, AERP waveforms, scalp topographies, and event-related potential-image plots were analyzed. A mixed design analysis of variance was used to compare the N400 amplitude and latency response between ears in both attentional modes. Independent component analysis was used to isolate temporally overlapping neural sources that contributed to the negativity in the latency range of the N400 component. N400 amplitude was significantly more negative in the DIV mode than DIR in both age groups. IA differences between age groups were evident only in DIV, as indicated by an age-related shift in the direction of IA in the N400 from greater asymmetry on the right in YAs to greater asymmetry on the left in MAs. ICA revealed that the age-related difference in IA in the AERP waveform reflected differences between YAs and MAs primarily in an electroencephalographic source process consistent with attentional processing. IA differences between YAs and MAs were revealed in the N400 only in DIV, which was the result of an increased information-processing load. ICA successfully separated temporally overlapping EEG sources that contributed to the N400 component, allowing a refined interpretation of differences in the AERP waveform among groups.

Sample Size Calculations for Precise Interval Estimation of the Eta-Squared Effect Size

Analysis of variance is one of the most frequently used statistical analyses in the behavioral, educational, and social sciences, and special attention has been paid to the selection and use of an appropriate effect size measure of association in analysis of variance. This article presents the sample size procedures for precise interval estimation of eta-squared and partial eta-squared in fixed-effects analysis of variance designs. The desired precision of a confidence interval is assessed with respect to (a) the control of expected width and (b) the tolerance probability of interval width within a designated value. In addition, sample size calculations for standardized contrasts of treatment effects and corresponding partial strength of association effect sizes are also considered.

Topiramate impairs cognitive function in cocaine-dependent individuals maintained on methadone

Topiramate impairs cognitive function in cocaine-dependent individuals maintained on methadone

Differences in mood and quality of life indicators by HIV status in a group of methamphetamine-dependent individuals

Differences in mood and quality of life indicators by HIV status in a group of methamphetamine-dependent individuals

Acute Ischemic Stroke Brainwave Classification Using Relative Power Ratio Cluster Analysis

This study proposed the application of cluster analysis to classify the brainwaves of stroke level based on the Relative Power Ratio (RPR) techniques. RPR was performed to determine the brainwave characteristics due to group of stroke level. In this research, we determined seventy four stroke patients brainwave activity with open eyes (OE) session. Then group them into Advance Group (AG), Intermediate Group (IG) and Early Group (EG). Simultaneously, their Electroencephalogram (EEG) was recorded from which the EEG dataset will be calculated using the RPR formula. Beta, Alpha, Theta and Delta Power Spectrum Density (PSD) are used as input for RPR. The results show that by implementing RPR technique, the pattern of group stroke level, especially in the cognitive or thinking abilities can be clearly observed. Then cluster analysis using a factorial ANOVA (analysis of variance) design with factors Group will be deployed to cluster RPR towards the corresponding group of stroke level. It can be concluded that the AG are higher in the cluster 1 for RPR Beta (RPRB) while IG and EG were grouped together because they do not differ from each other in cluster 2. For RPR Alpha (RPRA), EG are higher in the cluster 2 while AG and IG were grouped together in cluster 1. AG was found in both clusters for RPR Theta (RPRT) and AG are lower in cluster 1 for RPR Delta (RPRD). This indicates that the group stroke level can discriminate due to the brainwaves characteristics.

Determining Sample Size With a Given Range of Mean Effects in One-Way Heteroscedastic Analysis of Variance

The authors examined 2 approaches for determining the required sample size of Welch's test for detecting equality of means when the greatest difference between any 2 group means is given. It is shown that the actual power obtained with the sample size of the suggested approach is consistently at least as great as the nominal power. However, the sample size given by the method of Guo and Luh (2008) does not always guarantee the minimum power performance. Furthermore, the computed sample size and associated power of their formula tend to be larger than those provided with the proposed procedure. A supplementary computer program is provided to aid the implementation of the proposed technique in planning analysis of variance designs.

Electrophysiological Evidence of Augmented Interaural Asymmetry in Middle-Aged Listeners

Various dimensions of auditory processing, especially the perception of speech in the presence of background competition, have been shown to deteriorate with age. A persistent problem in the assessment of these age-related changes has been the high prevalence of age-related high-frequency hearing loss in elderly persons. Some investigators have suggested that a more fruitful approach to the study of age-related decline might be to study middle-aged, rather than elderly, persons, where confounding high-frequency hearing loss is less prevalent. To determine whether an increase in the left-ear disadvantage (LED) in dichotic listening could be demonstrated in a group of middle-aged persons. The N400 component of the auditory event-related potential (AERP) was utilized to evaluate interaural asymmetry in a quasi-dichotic competing speech task. Electrophysiological responses were obtained on a word-pair semantic categorization task presented through a front loudspeaker while the listener ignored competing speech presented through either left (competition left [CL]) or right (competition right [CR]) loudspeakers. Study Samples: Twenty young (18-24 yr) and 20 middle-aged (44-57 yr) females with normal hearing sensitivity. Individual, as well as grand-averaged, AERP waveforms and scalp topographies were analyzed for the word pairs. Peak amplitude and latency measures of the N400 component were subjected to a mixed design analysis of variance (ANOVA). No significant interaural asymmetry was found in the AERP waveform for the reference word condition in either age group. In response to the second word of the pair, however, middle-aged females showed significantly greater N400 negativity in the CR condition than in the CL condition. No significant laterality effect was found in the young females. The study of young versus middle-aged participants may be an effective way of avoiding the confound of high-frequency hearing loss in elderly persons when studying age effects on auditory processing.

Considerations for Stimulus–Response Curves in Stroke: An Investigation Comparing Collection and Analysis Methods

ABSTRACTStimulus–response curves (SRCs) provide information about the neurophysiological strength of corticospinal connections. The method for measuring and/or drawing meaningful conclusions of SRCs has not been well established in the stroke population. This study sought to characterize the use of an abbreviated SRC in stroke by comparing two data collection and two analysis approaches. SRCs were obtained using transcranial magnetic stimulation (TMS) in 25 survivors of stroke. The SRC data were collected with TMS intensities referenced to either motor threshold (MT; 5% increments between 100% and 140% of MT) or stimulator output (5% increments between 30% and 100% output) with peak-to-peak motor evoked potential amplitudes determined and averaged for each intensity level. Data were modeled with a three-parameter sigmoid function and a linear regression and were analyzed with a mixed design analysis of variance. There was no difference in the accuracy of prediction (r2) between the different analyses. There were significant differences in the slope parameters depending on the analysis method, but this was not dependent on the SRC data collection method. A linear regression of the SRC accurately represents the slope of the modeled data and is strongly correlated with the calculated peak slope, yet is less computationally complex than the sigmoid function. This study demonstrates the use of a linear analysis approach for SRCs as outcome measures for stroke studies.

Deliberate laterality practice facilitates sensory-motor processing in developing children

Background: The innate ability for typically developing children to attain developmental motor milestones early in life has been a thoroughly researched area of inquiry. Nonetheless, as children grow and are required to perform more complex motor skills in order to experience success in physical activity and sport pursuits, the range of developmental abilities becomes increasingly variable. What is less known in the literature is if physical education and sport programmes deliberately designed to facilitate the motor development of these underlying abilities can improve the efficiency of purposeful movements in children.Purpose: To determine if the sensory-motor processing of lateral arm movements in children can be initiated quicker as a result of deliberate laterality practice.Participants and setting: Forty-five children (boys = 23, girls = 22), between the ages of 8 and 11 years, randomly selected from several Tasmanian (Australia) communities participated in this study. Each child participated in 1 day (∼90 min) of data collection in a laboratory at the university.Research design: A repeated measures design using upper-extremity choice reaction time (RT) tests, separated by a 30-min treatment was employed in the current study. To test the effects of deliberate laterality practice on processing speed, children were randomly assigned into contralateral ball-bouncing (CBB), ipsilateral ball-bouncing, or a control video-game group (n = 15 in each). The treatments were designed using tenants of Ericsson, Krampe, and Tesch-Romer's theory of deliberate practice on expert performance, and the specificity of the training principle commonly discussed in the exercise science literature.Data collection: On an individual basis, each participant performed 27 empirical trials of goal-directed aiming movements with each arm separately, during the pretest and post-test. The stimulus-response trials occurred randomly in three different directions at the same distance from the starting position (ipsilateral, contralateral, and midline).Data analysis: A 3 (treatment group) × 2 (test) × 2 (arm) × 3 (direction) mixed design analysis of variance with repeated measures on the last three factors was used to test for significant differences, with an alpha level set at 0.05.Findings: Results revealed the CBB group experienced significantly shorter RTs in the contralateral direction during the post-test, likewise the ipsilateral group had significantly shorter RTs in the ipsilateral direction after the treatment. Further, the control group exhibited longer RTs in the contralateral direction compared to their pretest.Conclusions: Even after a short bout of deliberate laterality practice, children were able to reduce the processing speed associated with their lateral movements. Practitioners in the field may utilize these findings to foster developmental readiness in children wishing to improve their ability to perform the more complex motor skills requisite for successful sport and physical activity participation.

A Default Bayesian Hypothesis Test for ANOVA Designs

This article presents a Bayesian hypothesis test for analysis of variance (ANOVA) designs. The test is an application of standard Bayesian methods for variable selection in regression models. We illustrate the effect of various g-priors on the ANOVA hypothesis test. The Bayesian test for ANOVA designs is useful for empirical researchers and for students; both groups will get a more acute appreciation of Bayesian inference when they can apply it to practical statistical problems such as ANOVA. We illustrate the use of the test with two examples, and we provide R code that makes the test easy to use.

The effect of institutionalization on psychomotor development of preschool aged children

Development can be altered by several factors which can either facilitate or obstruct development. The aim of the current study was the examination and the detection of differences in the developmental profiles of preschool aged children living in conventional institution facilities (N=28), in SOS villages (N=20) and in natural family environment (N=48). The psychomotor development of the 96 children, aged 4-6 years old, was assessed using the six scales of the Griffiths Test No II. Two-way analysis of variance designs showed that family reared children had better performance in all scales of the Griffiths test compared with children of the other two groups and that children living in a SOS village had better scores on all domains of development examined compared to children living in a conventional institution (p<.05). The findings reinforce the need to transform institution environments into more supportive ones for the most benefit of children's development and mental health.

A new approach for testing the Rasch model

Though calibration of an achievement test within psychological and educational context is very often carried out by the Rasch model, data sampling is hardly designed according to statistical foundations. However, Kubinger, Rasch, and Yanagida (2009) recently suggested an approach for the determination of sample size according to a given Type I and Type II risk, and a certain effect of model misfit when testing the Rasch model is supported by some new results. The approach uses a three-way analysis of variance design with mixed classification. There is a (fixed) group factor A, a (random) factor B of testees within A, and a (fixed) factor C of items cross-classified with . The simulation study in this article deals with further item parameter ranges and ability parameter distributions, and with larger sample sizes and item numbers than the original paper. The results are: The approach works given several restrictions, and its main aim, the determination of the sample size, is attained.

The in vitro and in vivo experimental study of long-circulating superparamagnetic iron oxide liposome nanoparticles as novel MR contrast agent

Objective To evaluate pharmacodynamics of prepared long-circulating superparamagnetic iron oxide (SPIO) liposomes. Methods Control and experimental groups were established after adding SPIO or long-circulating SPIO liposomes as agents. (1)Macrophages experiment in vitro: the RAW 264.7 macrophage cell strains were recovered, cultured and seeded in the culture plate at a density of 2.5×105 cells/well until they reached 80%-90% confluence. The intracellular Fe uptake of control and experimental group cells were quantified by Ferrozine assay after incubation with different concentrations of drugs. Factorial design analysis of variance was used as statistics method. Prussian blue staining method was used to detect staining of experimental cells.(2)Drug biodistribution in mice: C57BL/6J(n=6) were classified into blank control group (n=2), control group(n=2) and experimental group(n=2).Saline, SPIO and long circulating SPIO were injected via the tail vein in the blank control group, control group and experimental group respectively. Then distribution of drugs in the body was observed by pathological examination.(3) MR imaging of tumor-bearing nude mice: 20 BALB/c nude mice bearing lung cancer models were established and classified into control group and experimental group. After administration of drugs, all animals underwent MR scanning. Signal intensities of livers and tumors were measured, SNR-time dynamic curves were drew. Covariance analysis was used to compare post-enhanced SNR at the 12th hour. (4)Cytotoxicity studies (MTT): cytotoxicity of both drugs on human liver cell line HL-7702 was studied, and statistically analyzed using factorial design analysis of variance. Results (1) Macrophages experiment in vitro: The nanoparticle uptake by macrophage cells evaluated by ferrozine assay showed the uptake of blank SPIO was higher than long-circulating SPIO liposomes. Compared with the blank control group, there was strong blue staining in the macrophages with Prussian staining in the control group and little blue staining in the experimental group. (2) Drug biodistribution in mice: for blue stained cells composed of iron particles, the amounts in the liver, spleen, lung, kidney of the control group were more than those in the experimental group. (3) MR imaging of tumor-bearing nude mice: the non-enhanced SNR of livers and tumors in the control group and experimental group were 31.47 ± 0.56, 30.89 ± 1.41, 58.41 ± 0.61, 58.44 ± 1.08, respectively. After injecting of contrast agents, SNR of livers and tumors in the control group and experimental group were 17.00 ± 0.96, 22.29 ± 0.73, 58.50 ± 0.63, 52.47 ± 1.18, respectively. The covariance analysis showed that SNR of the livers in the control group after 12 hours was significantly lower than the experimental group (F=167.022, P=0.000); while the SNR of the tumors in the experimental group was significantly lower than the control group (F=266.106, P=0.000).(4) Cytotoxicity of nanoparticles by MTT method: the viability of HL-7702 cells tend to decrease with the increase of Fe concentration. Cytotoxicity in the long-circulating SPIO liposomes was lower than the SPIO(F=2256.204,P=0.000). Conclusions Long-circulating SPIO liposomes we prepared reveal suitable sizes, even distribution, and good anti-macrophage ability in vitro and in vivo. They have long circulation characteristic and T2 negative enhancement effect in the transplanted lung cancers, while they still maintain low cytotoxicity. Key words: Contrast media; Nanotechnology; Magnetic resonance imaging; Animals,laboratory

Stability Assessment of Silin Powerhouse Cavern Based on Displacement Back Analysis Method

A back analysis procedure synthetically using parameters sensitivity analysis based on orthogonal design variance analysis, support vector regression modeling of nonlinear relation between mechanical parameters and displacement, and a hybrid optimization algorithm of particle swarm optimizer (PSO) and differential evolution (DE), was proposed. Optimum values of elasto-plastic mechanic parameters of rock mass were identified using the back analysis procedure and the measured displacement data. Assigning to the numerical model the optimum values of parameters, numerical simulation of powerhouse construction process was carried out to investigate the reliability of result of back analysis and the stability of powerhouse cavern. The result shows that calculated displacements are in good agreement with the measured, the powerhouse cavern is stable and has a considerable safety margin, and the existing support system can satisfy the need of local stability of powerhouse.

Prehospital Emergency Removal of Football Helmets Using Two Techniques

Objective. To compare the Eject Helmet Removal (EHR) System with manual football helmet removal. Methods. This quasiexperimental counterbalanced study was conducted in a controlled laboratory setting. Thirty certified athletic trainers (17 men and 13 women; mean ± standard deviation age: 33.03 ± 10.02 years; height: 174.53 ± 12.04 cm; mass: 85.19 ± 19.84 kg) participated after providing informed consent. Participants removed a Riddell Revolution IQ football helmet from a healthy model two times each under two conditions: manual helmet removal (MHR) and removal with the EHR system. A six-camera, three-dimensional motion capture system was used to record range of motion (ROM) of the head. A digital stopwatch was used to time trials and to record a split time associated with EHR system bladder insertion. A modified Borg CR10 scale was used to measure the rating of perceived exertion (RPE). Mean values were created for each variable. Three pairwise t-tests with Bonferroni-corrected alpha levels tested for differences between time for removal, split time, and RPE. A 2 × 3 (condition × plane) totally within-subjects repeated-measures design analysis of variance (ANOVA) tested for differences in head ROM between the sagittal, frontal, and transverse planes. Analyses were performed using SPSS (version 18.0) (alpha = 0.05). Results. There was no statistically significant difference in perceived difficulty between EHR (RPE = 2.73) and MHR (RPE = 2.55) (t29 = 0.76; p = 0.45; d = 0.20). Manual helmet removal was, on average, 28.95 seconds faster than EHR (t29 = 11.44; p < 0.001). Head ROM was greater during EHR compared with MHR in the sagittal (t29 = 4.57; p < 0.001), frontal (t29 = 5.90; p < 0.001), and transverse (t29 = 8.34; p < 0.001) planes. Head ROM was also greater during the helmet-removal portion of EHR in the frontal (t29 = 4.44; p < 0.001) and transverse (t29 = 5.99; p < 0.001) planes, compared with MHR. Regardless of technique, sagittal-plane head ROM was greater than frontal- and transverse-plane movements (F2,58 = 241.47; p < 0.001). Conclusions. Removing a helmet manually is faster and creates slightly less motion than removing a helmet using the Eject system. Both techniques were equally easy to use. Future research should analyze the performance of the Eject system in other styles of football helmets and in helmets used in other sports such as lacrosse, motorsports, and ice hockey.

The Impact of Humor on Attitudes toward Persons with Disabilities

The purpose of this study was to determine the impact of humor on attitudes as measured by the Modified lssues of Disability Scale (MIDS) by comparing the effects of a humorous and a serious video designed to reduce negative attitudes toward persons with disabilities. Ninety-three undergraduate students at a southeastern university volunteered to. participate in the study. The participants were randomly assigned to one of three treatment groups. The first group viewed a serious video concerning disability, the second group viewed a humorous video concerning disability, and the third group viewed no video. A one-way model analysis of variance design was applied to the MIDS scores (dependent variable). Results revealed no significant differences between the attitude scores of the three groups. The results of the study highlight the need for further research on the impact of humor on attitudes toward persons with disabilities.

Resting-State Perfusion in Nonmedicated Schizophrenic Patients: A Continuous Arterial Spin-labeling 3.0-T MR Study

To determine whether well-described patterns of altered perfusion in schizophrenia can be identified by using continuous arterial spin labeling (CASL) with a whole-brain imaging sequence. This study was approved by the ethics committee of the local institutional review board, and written informed consent was obtained from all subjects. CASL was used to compare cerebral perfusion between 11 nonmedicated patients with schizophrenia and 25 healthy control subjects. Since antipsychotic medication may affect perfusion, only drug-free subjects were examined. Resting-state perfusion, as measured in terms of regional cerebral blood flow, was compared voxel wise by using an analysis of variance design in a statistical parametric mapping program, with patient age and sex as covariates. Compared with the healthy control subjects, the schizophrenic patients had extensive areas of hypoperfusion in the frontal lobes bilaterally, in the anterior and medial cingulate gyri, and in the parietal lobes bilaterally. Increased perfusion was observed in the cerebellum, brainstem, and thalamus of the schizophrenic patients as compared with the perfusion in these areas in the control subjects. CASL in schizophrenia revealed patterns of hypo- and hyperperfusion similar to the perfusion patterns in previously published positron emission tomographic and single photon emission computed tomographic studies. The advantages of CASL, including independence from injected contrast agents, no irradiation, and fast acquisition time, may facilitate intensive perfusion studies of the early recognition of schizophrenia and other psychiatric disorders, as well as longitudinal disease-monitoring research of these conditions.

Statistics for terrified biologists

Statistics for terrified biologists

Impaired Orthostatic Response in Patients With Type 2 Diabetes Mellitus After 48 Hours of Bed Rest

To compare the effect of bed rest on orthostatic responses of patients with type 2 diabetes mellitus and nondiabetic control subjects. Six patients with type 2 diabetes and 6 non-diabetic control subjects underwent 48 hours of bed rest and 48 hours of ambulatory activity in randomized order. A 10-minute tilt test was conducted before and after each period of hospitalization, and cardiovascular responses to 80 degrees head-up tilt were analyzed with use of a 2-factorial (study group and bed rest condition) analysis of variance design. We hypothesized that patients with diabetes would experience more severe changes in orthostatic response after bed rest. No significant differences in orthostatic responses were observed before bed rest between control subjects and patients with diabetes. After bed rest, control subjects had a greater (P = .01) increase in heart rate during tilt in comparison with before bed rest (before versus after bed rest, 9 +/- 4 versus 24 +/- 7 beats/min) and maintained their blood pressure during tilt. After bed rest, patients with diabetes did not have a compensatory increase in heart rate and had a greater (P = .02) decline in systolic blood pressure during tilt in comparison with before bed rest (before versus after bed rest, -7 +/- 10 versus -21 +/- 11 mm Hg). Their arm and leg skin vasomotor responses (laser Doppler flowmetry) during tilt were not altered after bed rest and were similar to those in control subjects before and after bed rest. Cardiac neuropathy in patients with type 2 diabetes may prevent a compensatory heart rate response after bed rest deconditioning and result in a more severe orthostatic response. A greater decrease in blood pressure with upright tilt is evident after a relatively short period of bed rest.

The Simplest Chronoscope: Group and Interindividual Differences in Visual Reaction Time

The use of the simplest chronoscope (a falling meterstick) to measure visual reaction time (RT) in college students of both sexes is described. Tests of three hypotheses showed that (1) mean simple RT was significantly faster than long-standing population approximations and (2) a single-factor, repeated-measures, sequential-treatment analysis of variance design replicated Donders' long-standing findings that simple RT was significantly faster than choice RT; simple RT was significantly faster than discriminative RT; and that discriminative RT was significantly faster than choice RT. Also, (3) eta-squared effect size (eta2) computed on significant interindividual subject differences accounted for more variability than the eta2 effect size computed on significant differences between treatments. It was concluded that (1) the simplest chronoscope's methodology may have contributed to the significantly faster mean simple RT; (2) interindividual differences in RT should no longer be routinely ignored or eliminated; and (3) a repeated-measures analysis of variance design which tests for both group and interindividual differences can yield reaction time results of interest to both experimental and differential psychology.