Biomedical subjects

Tenko Raykov

Publications and source records attributed to Tenko Raykov.

11 recordsLinked to original sources

PubMed2006

Maximal reliability and power in covariance structure models.

In covariance structure modelling, the non-centrality parameter of the asymptotic chi-squared distribution is typically used as an indicator of asymptotic power for hypothesis tests. When a latent linear regression is of interest, the contribution to power by the maximal reliability coefficient, which is associated with used latent variable indicators, is examined and this relationship is further explicated in the case of congeneric measures. It is also shown that item parcelling may reduce power of tests of latent regression parameters. Recommendations on weights for parcelling to avoid power loss are provided, which are found to be those of optimal linear composites with maximal reliability.

Humans↗

PubMed2005

A method for testing group differences of scale validity in multiple population studies.

A method for testing equality in validity of multi-component measuring instruments across populations is outlined. The approach is developed within the framework of covariance structure modelling and complements earlier research on examining group differences in scale reliability. The procedure is particularly useful for purposes of ascertaining comparability of validity when constructing and developing measuring instruments. The method also provides ranges of plausible values for differences in composite validity across several populations and allows one to evaluate group discrepancies in validity of behavioural scales. The approach is illustrated using data from a cognitive intervention study.

Aged↗

PubMed2005

Studying group and time invariance in maximal reliability for multiple-component measuring instruments via covariance structure modelling.

A method for examining invariance in maximal reliability for weighted combinations of congeneric measures is described. The approach is developed within the framework of covariance structure modelling and allows one to ascertain whether a multi-component instrument consisting of homogeneous measures is associated with the same minimal relative error variance in distinct populations or over time. The procedure yields as a by-product an interval measure of discrepancy in maximal reliability across independent groups or assessment occasions, and is illustrated with two examples.

Humans↗

PubMed2005

Estimation of reliability for multiple-component measuring instruments in test-retest designs.

A covariance structure modelling method for the estimation of reliability for composites of congeneric measures in test-retest designs is outlined. The approach also allows an approximate standard error and confidence interval for scale reliability in such settings to be obtained. The procedure further permits measurement error components due to possible transient condition influences to be accounted for and evaluated, and is illustrated with a pair of examples.

Confidence Intervals↗

PubMed2005

Examining change in maximal reliability for multiple-component measuring instruments.

A method for examining change in maximal reliability for pre-specified sets of congeneric measures when developing a multi-component instrument is outlined. The approach is applicable for purposes of estimation and testing of gain or loss in the maximal reliability coefficient as a consequence of adding or dropping one or more measures from a homogeneous composite with uncorrelated errors, as well as when one is concerned with optimal component choice for highest increase or correspondingly smallest drop in maximal reliability. The method is compared with a procedure for ascertaining change in unweighted sum score reliability, and implications for instrument construction and revision are discussed. The approach is illustrated with a numerical example.

Analysis of Variance↗

PubMed2004

Stability and change in social negativity in later life: reducing received while maintaining initiated negativity.

OBJECTIVE: This article examines stability and change in social negativity and the links between social negativity and instrumental support over time among disabled older adults. The analyses focused on family relationships because social negativity tends to be more prevalent in family compared with nonkin relationships. Social negativity received and initiated are each addressed separately to determine whether or not they show similar patterns and links to instrumental support over time. METHODS: Latent growth curve methodology was used to examine change over time in social negativity and instrumental family support in relation to age, gender, and family network size at baseline. Participants, 570 older adults with chronic visual impairment, were interviewed three times over an 18-month period. RESULTS: Social negativity received showed a decrease over time, whereas levels of social negativity initiated remained more stable. Links with instrumental support were positive but stronger for received compared with initiated social negativity. DISCUSSION: The differential pattern of stability and change over time in received versus initiated social negativity and their links to instrumental support suggest different origins for the initiation versus receipt of social negativity.

Affect↗

PubMed2004

Examining time-invariance in reliability in multi-wave, multi-indicator models: a covariance structure analysis approach accounting for indicator specificity.

A covariance structure analysis method for testing time-invariance in reliability in multiwave, multiple-indicator models in outlined. The approach accounts for observed variable specificity and permits, in addition, estimation of reliability in terms of 'pure' measurement error variance. The proposed procedure is developed within a confirmatory factor analysis framework and illustrated with data from a cognitive intervention study.

Humans↗

PubMed2004

Estimation of maximal reliability: a note on a covariance structure modelling approach.

A one-step covariance structure analysis procedure for estimation of maximal reliability of linear composites with congeneric measures is outlined. The approach is readily employed within a single modelling session using popular covariance structure analysis software, and permits simultaneous estimation of the optimal measure weights with standard errors. The method is illustrated by a numerical example.

Humans↗

PubMed2002

Correlates of change in functional status of institutionalized geriatric schizophrenic patients: focus on medical comorbidity.

OBJECTIVE: Impairment in basic self-care skills is common in patients with schizophrenia and is even more severe in elderly patients with a chronic course of institutional care. While cognitive impairment has proven to be a major predictor of overall functional deficit in schizophrenia, other potential factors, such as medical comorbidity, need to be considered. METHOD: Geriatric institutionalized schizophrenic patients (N=124) were assessed three times over 4 years to determine levels of positive and negative symptoms, impairment in activities of daily living, impairment in cognitive functioning, and medical problems. Path analysis was used to determine which variables best predicted changes in self-care functions. RESULTS: Functional status, negative symptoms, cognitive functions, and health status all significantly worsened during the follow-up. The path analyses showed that change in health status did not predict change in activities of daily living after the analysis accounted for negative symptoms and cognitive functions. DISCUSSION: The results highlight the relative importance of cognitive impairments in the functional impairments of older schizophrenic patients with increased medical burden.

Activities of Daily Living↗

PubMed2002

Examining group differences in reliability of multiple-component instruments.

A covariance structure modelling method for examining group differences in scale reliability of multi-component measuring instruments is proposed. The procedure is based on a set of appropriate parameter constraints imposed in a multiple-population structural model. Unlike tests of group differences in coefficient alpha that in general do not evaluate the discrepancies in scale reliability coefficients, the described approach permits one to examine differences in the latter quantities of actual interest when concerned with questions pertaining to reliability of composite scores. The method can be used to test whether a given measuring instrument has identical reliabilities in studied populations, and/or whether distinct instruments, or modes of administration of the same instrument, have equal reliabilities across groups. The proposed procedure is illustrated with a pair of examples.

Humans↗

PubMedDate not supplied

A comparative study of two psychometric approaches to detect risk status for dementia.

This study results from an effort to examine the relationship between the diagnostic potentials for detecting risk status for dementia of a cognitive plasticity approach and a traditional status-oriented procedure (test battery) by Storandt et al. [Arch Neurol 1984;41:497-499]. The aim is to compare prediction accuracy for risk for developing dementia with these two approaches. A sample of 106 community-dwelling elderly adults were tested with both procedures, and their scores on the Structured Interview for the Diagnosis of Dementia used as external criterion for predicting risk status. The findings show that figural relations pretest and training gains account for a considerable amount of individual differences in mental status similar to that explained by the traditional test battery. In addition, the accuracy of discrimination between healthy and at-risk participants appears slightly higher when using the figural pretest and training gains. These results suggest the conclusion that use of figural relations tests and the cognitive plasticity approach represents a viable alternative to the traditional, status-oriented test battery as a means of early diagnosis of dementia in nonclinical populations.

Aged↗