SEARCH · PubMed Health

Results for “Internal validation”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23Linked to original sources

PubMed2002

Studying pretrial publicity effects: new methods for improving ecological validity and testing external validity.

Although research examining the effects of pretrial publicity (PTP) on individuals' appraisals of a defendant and verdict decision making generally has been found to be internally valid, the external validity has been questioned by some social scientists as well as lawyers and judges. It is often proposed that the verisimilitude (or ecological validity) ofthe research should be increased in the service of increasing external validity; however, increasing verisimilitude can be costly in terms of both time and money. It is proposed that the Internet is a viable means of conducting PTP research that allows high verisimilitude without high costs. This is demonstrated with a study in which we used the Internet to examine PTP effects in an actual trial as it was taking place. Successful use of the Internet to conduct experimental research in other areas of psychology and law is discussed, as well as the importance of future research examining whether independent variables interact with methods in ways that undermine the generalizability of research findings.

Adult↗

PubMed2003

The OECD program to validate the rat uterotrophic bioassay. Phase 2: dose-response studies.

The Organisation for Economic Co-operation and Development has completed phase 2 of an international validation program for the rodent uterotrophic bioassay. The purpose of the validation program was to demonstrate the performance of two versions of the uterotrophic bioassay, the immature female rat and the adult ovariectomized rat, in four standardized protocols. This article reports the dose-response studies of the validation program; the coded single-dose studies are reported in an accompanying paper. The dose-response study design used five selected weak estrogen agonists, bisphenol A, genistein, methoxychlor, nonylphenol, and o,p -DDT. These weak agonists were administered in a prescribed series of doses to measure the performance and reproducibility of the protocols among the participating laboratories. All protocols successfully detected increases in uterine weights when the weak agonists were administered. Within each protocol, there was good agreement and reproducibility of the dose response among laboratories with each substance. Substance-specific variations were observed in the influence of the route of administration on the uterine response, the potency as related to the dose producing the first statistically significant increase in uterine weights, and the maximum increase in uterine weight. Substantive performance differences were not observed between the uterotrophic bioassay versions or among the standardized protocols, and these were judged to be qualitatively equivalent. It is noteworthy that these results were reproducible under a variety of different experimental conditions (e.g., animal strain, diet, housing, bedding, vehicle, animal age), indicating that the bioassay's performance as a screen is robust. In conclusion, both the intact, immature, and adult OVX versions, and all protocols appear to be reproducible and transferable across laboratories and are able to detect weak estrogen agonists.

Age Factors↗

PubMed2004

Internal consistency and validity of a new physical workload questionnaire.

AIMS: To examine the dimensionality, internal consistency, and construct validity of a new physical workload questionnaire in employees with musculoskeletal complaints. METHODS: Factor analysis was applied to the responses in three study populations with musculoskeletal disorders (n = 406, 300, and 557) on 26 items related to physical workload. The internal consistency of the resulting subscales was examined. It was hypothesised that physical workload would vary among different occupational groups. The occupations of all subjects were classified into four groups on the basis of expected workload (heavy physical load; long lasting postures and repetitive movements; both; no physical load). Construct validity of the subscales created was tested by comparing the subscale scores among these occupational groups. RESULTS: The pattern of the factor loadings of items was almost identical for the three study populations. Two interpretable factors were found: items related to heavy physical workload loaded highly on the first factor, and items related to static postures or repetitive work loaded highly on the second factor. The first constructed subscale "heavy physical work" had a Cronbach's alpha of 0.92 to 0.93 and the second subscale "long lasting postures and repetitive movements", of 0.86 to 0.87. Six of eight hypotheses regarding the construct validity of the subscales were confirmed. CONCLUSIONS: The results support the internal structure, internal consistency, and validity of the new physical workload questionnaire. Testing this questionnaire in non-symptomatic employees and comparing its performance with objective assessments of physical workload are important next steps in the validation process.

Adult↗

PubMed2003

Evaluation of two devices for self-measurement of blood pressure according to the international protocol: the Omron M5-I and the Omron 705IT.

BACKGROUND: Two devices for self-measurement of blood pressure at the brachial artery-the Omron M5-I and the Omron 705IT-were evaluated according to the international protocol of the European Society of Hypertension. DESIGN: The international validation protocol is divided into two phases: the first phase is performed on 15 selected subjects and if the device passes this phase, 18 supplementary subjects are included making a total number of 33 subjects on which the final validation is performed. METHODS: For each subject, four blood pressure (BP) measurements were performed simultaneously by two trained observers using mercury sphygmomanometers alternately with three measurements by the tested device. The difference between the BP value given by the device and that obtained by the two observers (mean of the two observers) was calculated for each measure. The 99 differences were classified into categories (<or=5, <or=10, <or=15 mmHg). The number of differences in each category was compared to the number required by the international protocol. An individual analysis was then done to determine for each subject the number of comparisons <or=5 mmHg. At least 22 of the 33 subjects should have two of their three comparisons <or=5 mmHg. RESULTS: The two tested devices passed the first phase of the validation process. For the second phase, the average differences between the device and mercury sphygmomanometer readings were -0.9+/-5.8 and -0.8+/-4.8 mmHg for systolic blood pressure (SBP) and diastolic blood pressure (DBP) respectively for the Omron M5-I device and -0.2+/-4.5 and -2.0+/-4.8 mmHg for the Omron 705IT device. Readings for the two devices differing by less than 5, 10 and 15 mmHg for systolic and diastolic values fulfil the recommendation criteria of the international protocol as well as the individual analysis. CONCLUSIONS: The Omron M-5I and the Omron 705IT devices pass the validation recommendations of the international protocol.

Adult↗

PubMed2003

The OECD program to validate the rat uterotrophic bioassay. Phase 2: coded single-dose studies.

The Organisation for Economic Co-operation and Development has completed phase 2 of an international validation program for the rodent uterotrophic bioassay. This portion of phase 2 assessed the reproducibility of the assay with a battery of positive and negative test substances. Positive agonists of the estrogen receptor included the potent reference estrogen 17-ethinyl estradiol (EE), and the weak estrogen agonists bisphenol A, genistein, methoxychlor, nonylphenol, and o,p -DDT. The negative test substance or nonagonist was n-dibutylphthalate. The test substances were coded, and prescribed doses of each test substance were administered in 16 laboratories. Two versions of the uterotrophic assay, the intact immature and the adult ovariectomized female rat, were tested and compared using four standardized protocols covering both sc and po administration. Assay reproducibility was compared using a) EE doses identical to those used in phase 1 and in parallel dose-response studies, b) single doses of the weak agonists identical to one of five doses from the dose-response studies, and c) a single dose of the negative test substance. The results were reproducible and in agreement both within individual laboratories and across the participating laboratories for the same test substance and protocol. The few exceptions are examined in detail. The reproducibility was achieved despite a variety of different experimental conditions (e.g., variations in animal strain, diet, housing protocol, bedding, vehicle, animal age). In conclusion, both versions of the uterotrophic bioassay and all protocols appear robust, reproducible, and transferable across laboratories and able to detect weak estrogen agonists. These results will be submitted along with other data for independent peer review to provide support for the validation of the uterotrophic bioassay.

Animal Feed↗

PubMed2005

Predicting genotoxicity of aromatic and heteroaromatic amines using electrotopological state indices.

A quantitative structure-activity relationship (QSAR) model relating electrotopological state (E-state) indices and mutagenic potency was previously described by Cash [Mutat. Res. 491 (2001) 31-37] using a data set of 95 aromatic amines published by Debnath et al. [Environ. Mol. Mutagen. 19 (1992) 37-52]. Mutagenic potency was expressed as the number of Salmonella typhimurium TA98 revertants per nmol (LogR). Earlier work on the development of QSARs for the prediction of genotoxicity indicated that numerous methods could be effectively employed to model the same aromatic amines data set, namely, Debnath et al.; Maran et al. [Quant. Struct.-Act. Relat. 18 (1999) 3-10]; Basak et al. [J. Chem. Inf. Comput. Sci. 41 (2001) 671-678]; Gramatica et al. [SAR QSAR Environ. Res. 14 (2003) 237-250]. However, results obtained from external validations of those models revealed that the effective predictivity of the QSARs was well below the potential indicated by internal validation statistics (Debnath et al., Gramatica et al.). The purpose of the current research is to externally validate the model published by Cash using a data set of 29 aromatic amines reported by Glende et al. [Mutat. Res. 498 (2001) 19-37; Mutat. Res. 515 (2002) 15-38] and to further explore the potential utility of using E-state sums for the prediction of mutagenic potency of aromatic amines.

Amines↗

PubMed1996

Prediction of body cell mass, fat-free mass, and total body water with bioelectrical impedance analysis: effects of race, sex, and disease.

The inability to precisely estimate body composition with simple, inexpensive, and easily applied techniques is an impediment to clinical investigations in nutrition. In this study, predictive equations for body cell mass (BCM), fat-free mass (FFM), and total body water (TBW) were derived from direct measurements through use of single-frequency bioelectrical impedance analysis (BIA) in 332 subjects, including white, black, and Hispanic men and women, who were both healthy control subjects and patients infected with the human immunodeficiency virus (HIV). Preliminary studies showed more accurate predictions of BCM when parallel-transformed values of reactance were used rather than the values reported by the bioelectrical impedance analyzer. Modeling equations derived after logarithmic transformation of height, reactance, and impedance were more accurate predictors than equations using height2/resistance, and the use of sex-specific equations further improved accuracy. The effect of adding weight to the modeling equation was less important than the BIA measurements. The resulting equations were validated internally, and race and disease (HIV infection) were shown not to affect the predictions. The equation for FFM was validated externally against results derived from hydrodensitometry in 440 healthy individuals; the SEE was < 5%. These results indicate that body composition can be estimated with simple and easily applied techniques, and that the estimates are sufficiently precise for use in clinical investigation and practice.

Adult↗

PubMed1995

The health-related physical activity of children.

The fitness and physical activity levels of children and youth are commonly questioned, but the evidence cited is both equivocal and methodologically diverse. The amount and type of physical activity undertaken during childhood that is appropriate for optimal health is unknown, although it has been suggested that, in the absence of such criteria, activity levels known to confer health benefits in adults are also appropriate for children. The measurement of activity in children is problematical, and there is currently no valid method of assessing activity levels that is feasible for use in large studies. Therefore, studies may lack either internal validity or wider applicability. Studies using self-report methods indicate relatively high levels of activity with 60 to 70% of children taking sufficient 'appropriate' physical activity. However, a variety of activity thresholds have been used. Studies that use more objective methods report much lower levels of activity, especially when cardiovascular fitness criteria are applied. The use of less stringent health-related thresholds results in higher levels of 'appropriate' activity. Nearly all studies of teenagers report a decline in activity with age during this period. Data from the large population studies indicate that activity levels peak in children at around 13 to 14 years of age, and then markedly decline. Boys are normally reported to be more active than girls, but this difference is greatly reduced when moderate activity alone is compared, indicating that boys participate in more vigorous exercise than girls. The health effects of low levels of vigorous activity in children are unclear.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed2003

World Health Organization Quality of Life Assessment: brief version in Bahasa Malaysia.

WHOQOL-100, a 100 items quality of life assessment by WHO is too lengthy to be applicable in researches where the quality of life is one of the many variables of interest. The abbreviated version with 26 items is more acceptable by subjects, especially those with illness. The generic and the abbreviated Malay version were given to subjects who were healthy and with illness. Results showed that the domain scores produced by WHOQOL-BREF correlate highly with that of WHOQOL-100. WHOQOL-BREF domain scores demonstrated good discriminant validity, construct validity, internal consistency and test-retest reliability. The study indicates that WHOQOL-BREF in its brevity offers a valid and reliable assessment of quality of life.

Health Surveys↗

PubMed1986

Construct validity of the DSM-III and RDC classification of melancholia (endogenous depression).

Diagnostic schedules for any psychiatric disorder should represent a coherent concept and demonstrate adequate construct (internal) validity and transferability. Testing fit to latent class models (e.g. by Rasch model fitting test), correspondence to these requirements can be assessed. Based on data from a sample of 173 depressed in-patients, diagnostic schedules for endogenous depression (melancholia) according to DSM-III and RDC are evaluated for their ability to fit the requirements listed above. According to the data presented, the set of DSM-III-criteria for melancholia represents a coherent concept; on the contrary, this is not the case for RDC-criteria. Furthermore, application of the diagnostic algorithm applied to the defining criteria according to DSM-III has been justified; again, this was not the case for the diagnostic algorithm according to RDC. However, a simple linear diagnostic algorithm emerges from our data.

Adult↗

PubMedDate not supplied

Assessment of DSM-III personality structure in a general-population survey.

The object of this study is to assess the internal validity of DSM-III personality constructs and to explore whether the constituent elements are better explained by an alternate internally coherent classification. A two-stage stratified random sample of subjects identified at the Baltimore site of the Epidemiologic Catchment Area (ECA) program were examined by psychiatrists for DSM-III personality attributes using a semistructured instrument. Dichotomous factor analysis was used in the confirmatory mode to test whether a single factor explained each of the 11 DSM-III personality disorders. This approach rejected a single explanatory factor for all but compulsive personality disorder. Exploratory factor analysis showed that these DSM-III personality features are parsimoniously described by a five-factor model. These factors are warmth, animation, timidity, trust, and scrupulousness.

Adolescent↗

PubMed2003

A practical approach to quality improvement: the experience of the RNZCGP practice standards validation field trial.

AIM: This paper describes the development, implementation and validation of general practice standards, supported by a continuous quality improvement (CQI) process that teaches practice teams how to work together to identify and enhance the quality of care they provide. METHODS: Practice standards were developed through consensus by key stakeholders in general practice, pre-tested in four practices, and refined and piloted in 20 practices throughout New Zealand during 1999. A further field trial was undertaken to validate the standards and test the process of practice assessment. During 2000-2001, 74 practices volunteered to be assessed against the standards. Sixty one general practitioners, practice nurses and practice managers, nominated from independent practitioner associations (IPAs) or primary care organisations (PCOs), were trained to undertake the assessments. RESULTS: On five of 13 variables, no statistically significant differences at the 0.05 level were identified between the practices in the field trial and a random sample of practices studied by Kljakovic. The Royal New Zealand College of General Practitioners (RNZCGP) standards were found to have excellent face validity and content validity, and good construct validity. Internal consistency was fair. Lessons from the evaluation have informed an improved version of the practice assessment tool. CONCLUSIONS: The validation field trial provided the RNZCGP with a framework and tool for an accreditation process based on the principles of CQI. The tool offers patients and other stakeholders a credible measure of quality and safety at the practice level through a process bridging quality control and quality improvement.

Accreditation↗

PubMedDate not supplied

Estimation of mental health care cost units for patients with schizophrenia.

INTRODUCTION: The disease-cost study, based on the study of cohorts of patients through their visits to the mental health system, requires knowledge on the cost of each health care unit. However, lack of standardized procedures limits the external validity of the results obtained. When methodological information regarding the procedures applied is available, it makes it possible to compare the internal validity and to understand the suppositions on which the cost estimations have been made. METHODS: Cost-units for the health care received by a cohort of patients diagnosed of schizophrenia were estimated. The study was performed by a community-based team and at several hospital premises belonging to the Andalusia Health Service. A sensitivity analysis was conducted whenever necessary. RESULTS: Both in inpatients and outpatients care, personnel represents the biggest cost, this proportion being higher within the outpatient care. Among the professional categories the care given by the psychiatrists is the most expensive. Time load is similar for the different categories except for the psychiatrist. CONCLUSIONS: Cost unit estimates are lower than that which has been published internationally and within Spain. However, the findings must be carefully considered due to the influence that the different methodological options may have.

Ambulatory Care↗

PubMed2004

Development of a diabetes diet-related quality-of-life scale.

OBJECTIVE: The purpose of this study was to assess the reliability and validity of the Diabetes Diet-Related Quality-of-Life (DDRQOL) scale, which is a measure of the influence of diet therapy on patients' quality of life (QOL). RESEARCH DESIGN AND METHODS: Patients with type 2 diabetes (n = 236) who were being treated on an outpatient basis were asked to complete the self-administered DDRQOL instrument. The factor validity, convergent and discriminant validity, internal consistency, and reproducibility of the DDRQOL scale were then assessed. Spearman's rank correlation coefficients among the DDRQOL scale and each of the SF-36 subscale scores were calculated to evaluate its convergent and discriminant validity. RESULTS: Based on the results of the factor analysis, the following seven subscales were adopted for the DDRQOL: "satisfaction with diet," "burden of diet therapy," "perceived merits of diet therapy," "general perception of diet," "restriction of social functions," "vitality," and "mental health." As hypothesized, the DDRQOL scale was associated with each of the SF-36 subscales, with convergent and discriminant validity being generally exhibited. Cronbach's alpha-coefficient was between 0.71 and 0.84, suggesting strong internal consistency. The intraclass correlation coefficient of the subscales, with the results of a test-retest conducted 2 weeks later, was between 0.46 and 0.75, suggesting some degree of reproducibility. CONCLUSIONS: These findings indicate that the DDRQOL scale has a reasonable degree of reliability and validity, and its application for the assessment of the needs of a patient's diet and the evaluation of diet education with regard to QOL is awaited.

Diabetes Mellitus, Type 2↗

PubMed2004

Development of a new measure to assess trunk impairment after stroke (trunk impairment scale): its psychometric properties.

OBJECTIVE: The purpose of this study was to investigate reliability, validity, internal structure, and responsiveness of our newly developed Trunk Impairment Scale (TIS) for patients with stroke. DESIGN: A total of 73 patients with stroke participated in this prospective study. Interrater reliability (weighted kappa statistics), content validity (principal component analysis), concurrent validity (Spearman's rank correlation with the Trunk Control Test), predictive validity (prediction of discharge FIM scores), and responsiveness (standardized response mean values) were examined. Internal consistency and item difficulties were analyzed with Rasch analysis. RESULTS: The weighted kappa of each TIS item ranged from 0.66 to 1.0. Principal component analysis revealed that the TIS measured a domain similar to the Stroke Impairment Assessment Set trunk items but different from the Stroke Impairment Assessment Set motor and visuospatial items. The TIS correlated with the Trunk Control Test (r = 0.91). To predict discharge FIM motor scores, addition of the TIS as one of the predictors to age, time from onset, and admission FIM score increased the adjusted R2 from 0.66 to 0.75. With Rasch analysis, the misfit was acceptable, except for the abdominal muscle strength item. The difficulty patterns were similar at admission and discharge, except for the abdominal muscle strength item. The responsiveness of the TIS was satisfactory and comparable with that of the Trunk Control Test (standardized response mean values, 0.94 and 1.06). CONCLUSIONS: Our newly developed TIS is reliable, valid, and responsive for use in stroke outcome research.

Adult↗

PubMedDate not supplied

Diagnostic PCR: validation and sample preparation are two sides of the same coin.

Increased use of powerful PCR technology for the routine detection of pathogens has focused attention on the need for international validation and preparation of official non-commercial guidelines. Bacteria of epidemiological importance should be the prime focus, although a "validation infrastructure" once established could easily be adapted for PCR-based detection of viruses and parasites. The aim of standardization should be the widespread adoption of diagnostic PCR for routine pathogen testing. European experience provides the impetus for realization of this vision through preparation of quantitative reference DNA material and reagents, production of stringent protocols and tools for thermal cycler performance testing, uncomplicated sample preparation techniques, and extensive ring trials for assessment of the efficacy of selected matrix/pathogen detection protocols.

Humans↗

PubMed2006

Short forms of the Child Perceptions Questionnaire for 11-14-year-old children (CPQ11-14): development and initial evaluation.

BACKGROUND: The Child Perceptions Questionnaire for children aged 11 to 14 years (CPQ11-14) is a 37-item measure of oral-health-related quality of life (OHRQoL) encompassing four domains: oral symptoms, functional limitations, emotional and social well-being. To facilitate its use in clinical settings and population-based health surveys, it was shortened to 16 and 8 items. Item impact and stepwise regression methods were used to produce each version. This paper describes the developmental process, compares the discriminative properties of the resulting four short-forms and evaluates their precision relative to the original CPQ11-14. METHODS: The item impact method used data from the CPQ11-14 item reduction study to select the questions with the highest impact scores in each domain. The regression method, where the dependent variable was the overall CPQ11-14 score and the independent variables its individual questions, was applied to the data collected in the validity study for the CPQ11-14. The measurement properties (i.e. criterion validity, construct validity, internal consistency reliability and test-retest reliability) of all 4 short-forms were evaluated using the data from the validity and reliability studies for the CPQ11-14. RESULTS: All short forms detected substantial variability in children's OHRQoL. The mean scores on the two 16-item questionnaires were almost identical, while on the two 8-item questionnaires they differed by only one score point. The mean scores standardized to 0-100 were higher on the short forms than the original CPQ11-14 (p < 0.001). There were strong significant correlations between all short-form scores and CPQ11-14 scores (0.87-0.98; p < 0.001). Hypotheses concerning construct validity were confirmed: the short-forms' scores were highest in the oro-facial, lower in the orthodontic and lowest in the paediatric dentistry group; all short-form questionnaires were positively correlated with the ratings of oral health and overall well-being, with the correlation coefficient being higher for the latter. The relative validity coefficients were 0.85 to 1.18. Cronbach's alpha and intraclass correlation coefficients ranged 0.71-0.83 and 0.71-0.77, respectively. CONCLUSION: All short forms demonstrated excellent criterion validity and good construct validity. The reliability coefficients exceeded standards for group-level comparisons. However, these are preliminary findings based on the convenience sampling and further testing in replicated studies involving clinical and general samples of children in various settings is necessary to establish measurement sensitivity and discriminative properties of these questionnaires.

Adolescent↗

PubMed2005

Validation of the AGILIS ambulatory blood pressure monitor according to the European Society of Hypertension International Protocol for validation of blood pressure measuring devices in adults.

BACKGROUND: We evaluated the clinical validity of the AGILIS ambulatory blood pressure monitor according to the European Society of Hypertension International Protocol. METHODS: The blood pressure (BP) was measured at the same arm by two certified observers using two mercury columns and a double stethoscope, then by the volunteer with the automatic device, these measurements were done seven times sequentially using 33 volunteers. For the randomization of the patient, one ABPM measure was compared to the mean of three manual measures. Then, we had three ABPM measures and four manual measures. Each ABPM measure, being compared to two manual measures. Blood pressure readings and recordings were blinded. Position of the subjects was standardized. RESULTS: Phase 1: To pass phase 1, the device had to have at least 25 of the 45 measurements within 5 mmHg, 35 within 10 mmHg or 40 within 15 mmHg of the comparative observer measurements. The AGILIS monitor had 35 measurements lying within 5 mmHg, 42 within 10 mmHg and 45 within 15 mmHg for systolic BP (SBP), 35 within 5 mmHg, 44 within 10 mmHg and 45 within 15 mmHg for diastolic BP (DBP). It passed the criteria for SBP and DBP. Phase 2: To pass phase 2.1, a device must have at least 60 of 99 measurements within 5 mmHg, 75 within 10 mmHg and 90 within 15 mmHg of the comparative observer measurements, and in addition must also have either 65 within 5 mmHg and 80 within 10 mmHg, or 65 within 5 mmHg and 95 within 15 mmHg, or 80 within 10 mmHg and 95 within 15 mmHg. The AGILIS monitor had 78 measurements within 5 mmHg, 91 within 10 mmHg and 96 within 15 mmHg for SBP; and 70 measurements within 5 mmHg, 92 within 10 mmHg and 96 within 15 mmHg for DBP. It passed the criteria for SBP and DBP. For phase 2.2 using the AGILIS monitor, 27 subjects had at least two of the differences within 5 mmHg and none had any differences within 5 mmHg for SBP; 27 subjects had at least two of the differences within 5 mmHg and three subjects had no differences within 5 mmHg for DBP. The results are in concordance with the requested criteria for phase 2.2. CONCLUSION: Thus the AGILIS device fulfils the validation criteria of the international protocol.

Adult↗