Bootstrap estimates of standard errors in validity generalization.

Bootstrapping is introduced as a method for approximating the standard errors of validity generalization (VG) estimates. A Monte Carlo study was conducted to evaluate the accuracy of bootstrap validity-distribution parameter estimates, bootstrap standard error estimates, and nonparametric bootstrap confidence intervals. In the simulation study the authors manipulated the sample sizes per correlation coefficient, the number of coefficients per VG analysis, and the variance of the distribution of true correlation coefficients. The results indicate that the standard error estimates produced by the bootstrapping procedure were very accurate. It is recommended that the bootstrap standard-error estimates and confidence intervals be used in the interpretation of the results of VG analyses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of sire, dam traits, calf traits, and environment on dystocia and subsequent reproduction of two-year-old heifers

This study examined the hypocholesterolemic effect and hormonal changes resulting from 30 d of supplementation with Vicia faba L. (field bean) flour of diets of young men (aged 18-21 y; n = 40) with borderline-high or high serum cholesterol values. All subjects (groups A-D) consumed the same basic diet. Additionally, volunteers in the control group (A) consumed 90 g control flour/d whereas those in the three bean groups received either 90 g cooked field bean flour (groups B and C) or 90 g raw field bean flour (group D) daily. Groups A and B included volunteers with borderline-high cholesterol values [5.2-6.2 mmol total cholesterol/L and 3.4-4.1 mmol low-density-lipoprotein (LDL) cholesterol/L]. Subjects in groups C and D had high serum cholesterol concentrations (total cholesterol > 6.2 mmol/L and LDL cholesterol > 4.1 mmol/L). After 30 d, serum glucose, insulin, triacylglycerol, total, LDL-cholesterol, and very-low-density-lipoprotein (VLDL)-cholesterol values were significantly lower than initial values in all subjects who consumed diets containing field bean flour (P < or = 0.0001, except for LDL-cholesterol concentrations in group C, for which P < or = 0.0007). Legume intake also resulted in a significant increase (P < or = 0.0001) in glucagon and high-density-lipoprotein cholesterol. Neither cortisol nor thyroid hormone values changed significantly. The results suggest that the hypocholesterolemic effect of field bean intake depends at least partly on a concomitant increase in glucagon and decrease in insulin values. The more marked reduction in triacylglycerol and VLDL-cholesterol concentrations in subjects who consumed raw field beans indicates a coparticipation of their thermolabile components.     

Large sample standard errors of kappa and weighted kappa.

2 statistics, kappa and weighted kappa, are available for measuring agreement between 2 raters on a nominal scale. Formulas for the standard errors of these 2 statistics are in error in the direction of overestimation, so that their use results in conservative significance tests and confidence intervals. Valid formulas for the approximate large-sample variances are given, and their calculation is illustrated using a numerical example. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conceptus, progesterone, and breed effects on uterine protein secretion in swine

This experiment consisted of the following treatment-breed groups: 1) White crossbred gilts, 2) White crossbred gilts treated with progesterone (200 mg/d in corn oil given on d 2 and 3 after estrus), and 3) Chinese Meishan gilts. Pregnant and nonpregnant gilts (n=3 to 6) from each treatment-breed combination were assigned to be slaughtered on d 10, 11, 12, 13, and 15. At slaughter each uterine horn was flushed with 20 mL of minimal essential medium. Uterine flushings were assayed for total protein, acid phosphatase, uteroferrin, retinol-binding protein, and oxytocin. Uterine flush total protein was increased by progesterone treatment, was unaffected by pregnancy status, and was less in Meishans. Similar patterns were found for retinol binding protein and uteroferrin, except that uteroferrin was greater in pregnant than in nonpregnant gilts. Oxytocin was greater in pregnant than in nonpregnant gilts, was not influenced by progesterone treatment, and was similar in Meishan and in White crossbred gilts. These results indicate that the conceptus does not influence secretion of either total protein or retinol binding protein during pregnancy and that the onset of secretion of these uterine proteins may be controlled by progesterone. The presence of the conceptus is associated with increased uteroferrin and oxytocin production. The decreased secretion of uterine proteins in Meishan gilts may partially explain the slower embryonic development that has been reported for this breed.     

Approximate standard errors and confidence intervals for indices of positive and negative agreement

Indices of positive and negative agreement for observer reliability studies, in which neither observer can be regarded as the standard, have been proposed. In this article, it is demonstrated by means of an example and a small simulation study that a recently published method for constructing confidence intervals for these indices leads to intervals that are too wide. Appropriate asymptotic (i.e., large sample) variance estimates and confidence intervals for the positive and negative agreement indices are presented and compared with bootstrap confidence intervals. We also discuss an alternative method of interval estimation motivated from a Bayesian viewpoint. The asymptotic intervals performed adequately for sample sizes of 200 or more. For smaller samples, alternative confidence intervals such as bootstrap intervals or Bayesian intervals should be considered.     

Random assignment of available cases: Bootstrap standard errors and confidence intervals.

A frequently used experimental design in psychological research randomly divides a set of available cases, a local population, between 2 treatments and then applies an independent-samples t test to either test a hypothesis about or estimate a confidence interval (CI) for the population mean difference in treatment response. C. S. Reichardt and H. F. Gollob (1999) established that the t test can be conservative for this design--yielding hypothesis test P values that are too large or CIs that are too wide for the relevant local population. This article develops a less conservative approach to local population inference, one based on the logic of B. Efron's (1979) nonparametric bootstrap. The resulting randomization bootstrap is then compared with an established approach to local population inference, that based on randomization or permutation tests. Finally, the importance of local population inference is established by reference to the distinction between statistical and scientific inference. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of lamb age, breed and sex on plasma LH after administration of GnRH

Male lambs of the Finn, Fingalway and High Fertility breeds aged 4 or 8 weeks of age were injected i.m. with 5, 10, 50, or 100 micrograms GnRH. Plasma LH after GnRH injection increased with age and GnRH dose but there was no effect of breed. There was no interaction among the three factors studied. In a second experiment the response of male and female lambs, aged 8 weeks, to 100 micrograms GnRH was investigated for 5 genetic groups (Finn, Galway Control, Galway Elite, Fingalway and High Fertility). Breed differences in plasma LH of male lambs were not found, which agreed with the result of the first experiment. Breed differences were observed for females, with the lowest values being observed for Finn and High Fertility lambs which represent the two most prolific breeds. This finding suggested breed differences in the development of the hypothalamic-pituitary-ovarian circuit. The difference between Galway Control and Galway Elite lambs was not significant (P greater than 0.10).     

Three standard errors of measurement and the Stanford-Binet Intelligence Scale, Fourth Edition.

The standard errors of measurement provided for the Stanford-Binet Intelligence Scale—Fourth Edition are (a) of limited utility and (b) set about an inappropriate score for use under most circumstances. Instructions are offered for calculating predicted true scores, and a table of standard errors of measurement is provided. In combination with the predicted true scores, the table can be used to set confidence intervals that will likely encompass an examinee's true score at the time of assessment and to calculate a confidence zone that will likely include an examinee's obtained score on retesting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Corrected estimates of WAIS—R short form reliability and standard error of measurement.

Corrects computation and rounding errors in composite reliability estimates for the summary measures of the complete Wechsler Adult Intelligence Scale--Revised (WAIS--R) and the 7-subtest short form (D. Schretlen, R. H. B. Benedict, and J. H. Bobholz; see record 1995-04011-001) to provide more accurate reliability and standard error of measurement information. Composite reliabilities for the summary scores with both WAIS-R forms and standard errors of measurement for the 7-subtest short form and the complete WAIS-R summary scores are presented. Standard deviations for the IQ scores are also summarized. These values differ from the sum of scaled scores that appear in the WAIS-R manual (D. Wechsler, 1981). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Repetition of semantic comparisons: Temporary and persistent priming effects.

Two experiments tested the involvement of both abstract semantic memory representations and instance-specific memory for feature encoding in repetition effects for a semantic processing task. Experiment 1 showed that a relatively small amount of facilitation (10%–25%) was attributable to memory for instance-specific features (typography) of repeated trials. Although small, this effect showed no decay over repetition lags investigated, suggesting persistent memory for encoded features or encoding processes. Experiment 2 showed that facilitation for semantically related repetitions was short-lived compared with facilitation for lexically exact repetitions. This suggested that priming of abstract semantic memory may be involved in temporary but not persistent repetition effects. Individual differences analyses supported the conclusion that despite the increased semantic complexity of this repetition priming task over those previously used, abstract semantic memory representations were not involved in persistent repetition effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Groupdrink: The effects of alcohol and group process on vigilance errors.

This research examined how group processes alter the impact of alcohol on a judgment task requiring vigilance. The authors compared two competing explanations, deindividuation and group monitoring, for the possible effects of alcohol. Two hundred and eighty-six undergraduates with normal drinking habits undertook a vigilance task alone or in four-person groups having consumed either alcohol (calculated to achieve up to .08 blood alcohol content) or a placebo. The vigilance task required them to count occurrences of the word "the" in a spoken passage. Alcohol significantly impaired the performance of individuals but not groups. Group members performed at a similar level in both conditions, making fewer errors than individuals in the alcohol condition. The fit of different decision-making models were tested. In both the alcohol and placebo conditions, group consensus was predicted by processes consistent with the group monitoring hypothesis. The evidence highlights that under certain conditions, group process can compensate for the cognitively impairing effects of alcohol on individuals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential effects of aging on directional and absolute errors in visuospatial memory.

Studied memory for visuospatial arrays in 28 male and 34 female healthy dextral adults (aged 20–90 yrs). 10 abstract figures were presented in each hemispace over a series of learning trials, and then delayed free recall of figure placement was obtained. Figures were misplaced significantly downward and leftward in both hemispaces. Both vertical and horizontal absolute error increased significanty with age, but no age effects on directional errors were observed. The increase in absolute error over age is consistent with decreased anterograde memory and visuospatial skills in the elderly. The directional errors are believed to result from an attentional shift toward proximal peripersonal space, in combination with attentional shifts from differential left vs right cerebral activation. Gender effects were also observed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Enduring effects of prenatal cocaine exposure on attention and reaction to errors.

Rats exposed to cocaine prenatally were administered a series of 3-choice visual attention tasks, with the most pronounced deficits seen in a task in which the onset time, location, and duration of a visual cue varied unpredictably between trials. The cocaine-exposed rats were less accurate than controls but did not differ in the rate of premature responses or omission errors. The pattern of errors, coupled with response latency data, implicated deficits in the ability to rapidly engage attention and maintain a high level of alertness to the task. The cocaine-exposed rats also exhibited a blunted reaction to an error on the previous trial, possibly reflecting an alteration in emotional regulation and/or error monitoring. Implications for underlying neuropathology are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of instructions on damage estimates from single photographs.

The ability of human observers to make magnitude estimates of damage was investigated under 3 instructional definitions of damage: (a) amount of volume reduction, or (b) amount of surface distortion or "complexity," or (c) overall amount of damage. The stimuli were distorted metal containers photographed from 5 angles of view between 0° and 90°. 9 college students were assigned to each of the 15 experimental groups. Analyses of errors in rating indicated that at least 2 subjectively different underlying damage scales could be discriminated but that these were highly correlated. Shape of the original, intact object is an important factor determining the magnitude and direction of errors. Interrater reliabilities of about .72 were obtained. (PsycINFO Database Record (c) 2010 APA, all rights reserved)