A Comparative Investigation of Confidence Intervals for IndependentVariables in Linear Regression

In linear regression, the most appropriate standardized effect size for individual independent variables having an arbitrary metric remains open to debate, despite researchers typically reporting a standardized regression coefficient. Alternative standardized measures include the semipartial correlation, the improvement in the squared multiple correlation, and the squared partial correlation. No arguments based on either theoretical or statistical grounds for preferring one of these standardized measures have been mounted in the literature. Using a Monte Carlo simulation, the performance of interval estimators for these effect-size measures was compared in a 5-way factorial design. Formal statistical design methods assessed both the accuracy and robustness of the four interval estimators. The coverage probability of a large-sample confidence interval for the semipartial correlation coefficient derived from Aloe and Becker was highly accurate and robust in 98% of instances. It was better in small samples than the Yuan-Chan large-sample confidence interval for a standardized regression coefficient. It was also consistently better than both a bootstrap confidence interval for the improvement in the squared multiple correlation and a noncentral interval for the squared partial correlation.     

Estimation of the Coefficient of Variation with Minimum Risk: A Sequential Method for Minimizing Sampling Error and Study Cost

The coefficient of variation is an effect size measure with many potential uses in psychology and related disciplines. We propose a general theory for a sequential estimation of the population coefficient of variation that considers both the sampling error and the study cost, importantly without specific distributional assumptions. Fixed sample size planning methods, commonly used in psychology and related fields, cannot simultaneously minimize both the sampling error and the study cost. The sequential procedure we develop is the first sequential sampling procedure developed for estimating the coefficient of variation. We first present a method of planning a pilot sample size after the research goals are specified by the researcher. Then, after collecting a sample size as large as the estimated pilot sample size, a check is performed to assess whether the conditions necessary to stop the data collection have been satisfied. If not an additional observation is collected and the check is performed again. This process continues, sequentially, until a stopping rule involving a risk function is satisfied. Our method ensures that the sampling error and the study costs are considered simultaneously so that the cost is not higher than necessary for the tolerable sampling error. We also demonstrate a variety of properties of the distribution of the final sample size for five different distributions under a variety of conditions with a Monte Carlo simulation study. In addition, we provide freely available functions via the MBESS package in R to implement the methods discussed.     

Stimulus–response correspondence effect as a function of temporal overlap between relevant and irrelevant information processing

The stimulus–response correspondence (SRC) effect refers to advantages in performance when stimulus and response correspond in dimensions or features, even if the common features are irrelevant to the task. Previous research indicated that the SRC effect depends on the temporal course of stimulus information processing. The current study investigated how the temporal overlap between relevant and irrelevant stimulus processing influences the SRC effect. In this experiment, the irrelevant stimulus (a previously associated tone) preceded the relevant stimulus (a coloured rectangle). The irrelevant and relevant stimuli onset asynchrony was varied to manipulate the temporal overlap between the irrelevant and relevant stimuli processing. Results indicated that the SRC effect size varied as a quadratic function of the temporal overlap between the relevant stimulus and irrelevant stimulus. This finding extends previous experimental observations that the SRC effect size varies in an increasing or decreasing function with reaction time. The current study demonstrated a quadratic function between effect size and the temporal overlap.     

Linked proximal and distal changes in the reaching behavior of 5- to 12-month-old human infants grasping objects of different sizes

This study evaluates age-related proximal and distal changes in reaching organization for objects of different sizes. To this end, eight objects ranging from 2 to 9 cm diam. were presented to 23 infants ages 5 to 12 months. Proximal control was determined by the relative frequencies of bimanual reaching for large and small objects. Distal control was assessed by hand opening and orientation with respect to an object, and by the proportion of the object being included within hand opening at touch. Five-month-old infants tended to reach bimanually regardless of object size. Starting at 7 to 8 months, infants tended to reach for large objects bimanually more often than for small ones. Only at 11 to 12 months did reaching closely reflect the object’s diameter. The frequency of thumb-index finger angle opening during the approach phase also increased after 7 to 8 months of age, as well as the adjustment of the angle to the object diameter and the proportion of the object within hand opening at touch. Proximal and distal changes appeared coupled at 5 to 6 months, when the few subjects showing evidence of some proximal adjustments to object size were also those who exhibited some distal adjustments. After they started to appear, however, proximal and distal adjustments seemed to be independent, as revealed by the lack of correlation of proximal and distal changes between 7 and 12 months.     

Relationships between factors of intelligence and brain volume

The recent explosion of studies aimed at determining the biological basis of intelligence has revealed that cognitive ability has a strong biological substrate. This study expands on this literature by examining the relation between cognitive ability and MRI-measured brain volume and head size in a sample of adult male siblings recruited from the London, Ontario community in Canada. It was found that brain volume correlated with IQ at 0.35 (P<0.01), thus replicating the results of past studies. Corrections for restriction of range and attenuation in both this and past studies suggest that the population value of the brain volume-IQ correlation is closer to 0.50. Head size variables, with one exception, also showed the expected positive correlations with IQ. The results of a vector analysis on factor scores indicated that the more highly g-loaded a test was the more highly it correlated with brain volume (r=0.59, P<0.01). The sum of the data suggested that although brain volume (and to a lesser extent, head size) is predictive of g, fluid ability, and memory, it does not predict crystallized ability. Unexpectedly, the higher the spatial imaging loading of a test, the less its correlation with brain volume (vector correlation=−0.84, P<0.001).     

方差分析效果大小报告的新指标

心理学期刊论文中可重复性不高的现象,原因之一是研究结果的效果普遍较小。并且在报告效果大小的文章中,效果大小指标使用不当。在方差分析中最经常报告的是η2和η2_p,但是在不同的研究设计中,这些效果大小是无法直接进行比较的。广义eta方(η²_G)是近年来新出现的一种新的效果大小指标,可克服的η2和η2_p不足,灵活处理重复测量等多种研究设计下个体差异的计算问题,实现跨研究设计效果大小的可比性。论文结合实例介绍了η²_G的原理和计算方法,并对其优缺点、使用和报告等问题进行了讨论。研究人员在报告效果大小时要考虑到不同的研究设计和研究假设,并选择恰当的指标防止过高估计效果大小。     

Reading and lexicalization in opaque and transparent orthographies: Word naming and word learning in English and Spanish

Do skilled readers of opaque and transparent orthographies make differential use of lexical and sublexical processes when converting words from print to sound? Two experiments are reported, which address that question, using effects of letter length on naming latencies as an index of the involvement of sublexical letter–sound conversion. Adult native speakers of English (Experiment 1) and Spanish (Experiment 2) read aloud four- and seven-letter high-frequency words, low-frequency words, and nonwords in their native language. The stimuli were interleaved and presented 10 times in a first testing session and 10 more times in a second session 28 days later. Effects of lexicality were observed in both languages, indicating the deployment of lexical representations in word naming. Naming latencies to both words and nonwords reduced across repetitions on Day 1, with those savings being retained to Day 28. Length effects were, however, greater for Spanish than English word naming. Reaction times to long and short nonwords converged with repeated presentations in both languages, but less in Spanish than in English. The results support the hypothesis that reading in opaque orthographies favours the rapid creation and use of lexical representations, while reading in transparent orthographies makes more use of a combination of lexical and sublexical processing.     

Estimating group size from human speech: Three's a conversation,but four's a crowd

Much previous research has examined various aspects of auditory processing, including the localization of sounds, and the influence of lexical and indexical information on language processing. In the present set of experiments we explored the ability of listeners to estimate the number of speakers in a group solely from the information in an auditory signal. The bound on accurately estimating the number of simultaneous speakers is 3. We suggest that subitization—the ability to estimate numerosity of visual and auditory elements without explicitly counting these elements—rather than the capacity of short-term memory, may underlie this limitation. The cognitive constraint on estimating the number of simultaneous speakers may have implications for a wide variety of seemingly unrelated psychological phenomena.     

Addressing the “Replication Crisis”: Using Original Studies to Design Replication Studies with Appropriate Statistical Power

Psychology is undergoing a replication crisis. The discussion surrounding this crisis has centered on mistrust of previous findings. Researchers planning replication studies often use the original study sample effect size as the basis for sample size planning. However, this strategy ignores uncertainty and publication bias in estimated effect sizes, resulting in overly optimistic calculations. A psychologist who intends to obtain power of .80 in the replication study, and performs calculations accordingly, may have an actual power lower than .80. We performed simulations to reveal the magnitude of the difference between actual and intended power based on common sample size planning strategies and assessed the performance of methods that aim to correct for effect size uncertainty and/or bias. Our results imply that even if original studies reflect actual phenomena and were conducted in the absence of questionable research practices, popular approaches to designing replication studies may result in a low success rate, especially if the original study is underpowered. Methods correcting for bias and/or uncertainty generally had higher actual power, but were not a panacea for an underpowered original study. Thus, it becomes imperative that 1) original studies are adequately powered and 2) replication studies are designed with methods that are more likely to yield the intended level of power.