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Results for “Internal validation”

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PubMed2006

[Violence scale and severity index: a methodological proposal for measuring violence by the partner in Mexican women].

OBJECTIVE: To construct and validate a scale to assess violence by the male partner against women. An index of severity of the emotional and physical damage was also designed to assess the intensity of the violent actions against women. MATERIAL AND METHODS: The sample consisted of a total of 26 042 women who participated as respondents in the National Survey on Violence against Women (ENVIM per its abbreviation in Spanish) conducted in Mexico during 2003. Respondents were all users of health services provided by the Mexican government. The questionnaire was organized into 17 sections, one of which was a 27-item scale to assess partner violence. The purpose of this scale was to measure the type (physical, emotional, sexual and financial) and degree of violence based on severity. A severity index was constructed based on two procedures: 1) the validity, reliability, and factor analyses of the scale and 2) the assessment of severity by expert judges who assigned a value to each item of the scale. RESULTS: The validity and reliability results indicated this scale has adequate internal validity (Cronbach's Alpha = 0.99). The factor analysis with Varimax rotation yielded a four-factor solution. The factors were: 1) Psychological violence; 2) Physical violence; 3) Severe physical violence; and 4) Sexual violence. The combination of the four factors accounted for 62.2% of the variance in the scale. Using the ratings from the judges a table of values for each of the violent actions described was obtained. The scores assigned by the judges ranged from 0 to 354. Results revealed a prevalence of 21% partner violence in the last twelve months. The prevalence of psychological violence was 18.5%; of physical violence 10.1%; severe physical violence 6.7% and sexual violence 7.0%. CONCLUSION: The scale of violence described in this article is a very useful and reliable instrument to assess marital violence against women. It is suggested that this instrument be used in other settings to compare results with different samples.

Battered Women↗

PubMed2002

[BREV: a rapid clinical scale for cognitive function evaluation in preschool and school-age children].

BREV, standing for the French "Batterie Rapide d'Evaluation des Fonctions Cognitive", is a rapid test to screen children with disorders of higher functions and to define the patterns of these disorders. We describe here two phases of the validation procedure. The first phase consisted in measuring the internal validity of the scale by testing 500 normal school children free of disability. The validation process provided appropriate values for each of the 18 subtests assessing cognitive functions (oral language, non-verbal abilities, attention and memory, education and memory, educational achievment) in ten age groups from 4 to 8 years. All subtests with the same content for any revealed values which increased significantly with age. Inter-reliability was tested by retesting 70 children. The second phase of validation, comparing BREV results and those from a large classical neuropsychological battery, tested specificity and sensitivity. Each of the BREV subtests were correlated with the similar subtest of the classical battery. Correlations between verbal and non-verbal scores and verbal and performance intellectual quotient (Weschler scale) were very significant. Sensitivity and specificity of BREV were above 75p.100;. This confirms the reliability of this battery for children, with good sensitivity and specificity. BREV is a reliable test, with carefully established norms, appropriate for preschool and school-age children.

Attention↗

PubMed2002

Validity of randomized clinical trials in gastroenterology from 1964-2000.

BACKGROUND & AIMS: The internal validity of clinical trials depends on the adequacy of the reported methodological quality. We assessed the methodological quality of all 383 randomized clinical trials published in GASTROENTEROLOGY as original articles from 1964 to 2000. METHODS: The methodological quality (randomization and blinding), sample size, publication year, and disease area were extracted from each trial. Changes during the study period were analyzed by analysis of variance with adjustments for potential confounders. RESULTS: Forty-two percent of all trials reported adequate generation of the allocation sequence, 39% reported adequate allocation concealment, and 62% were double blind. The reported methodological quality improved significantly in the mid-1990s. CONCLUSIONS: The present study shows a positive development, but the reported methodological quality of trials can still be improved.

Gastroenterology↗

PubMed2006

Single subject controlled experiments in aphasia: the science and the state of the science.

UNLABELLED: This paper discusses the use of single subject controlled experimental designs for investigating the effects of treatment for aphasia. A brief historical perspective is presented, followed by discussions of the advantages and disadvantages of single subject and group approaches, the basic requirements of single subject experimental research, and crucial considerations in design selection. In the final sections, results of reviews of published single subject controlled experiments are discussed, with emphasis on internal validity issues, the number of participants enrolled in published studies, operational specification of the dependent and independent variables, and reliability of measurement. LEARNING OUTCOMES: As a result of reading this paper, the participant will: (1) understand the mechanisms required for demonstration of internal and external validity using single subject controlled experimental designs, (2) become familiar with the basic requirements of single subject controlled experimental research, (3) understand the types of single subject controlled experimental designs that are the most appropriate for studying the effects of treatment for aphasia, and (4) become familiar with trends in the published aphasia treatment literature in which single subject controlled experimental designs have been used.

Aphasia↗

PubMed2004

The SCL-90 and SCL-90R versions validated by item response models in a Danish community sample.

OBJECTIVE: To evaluate the internal validity of the subscales of the combined SCL-90 and SCL-90R, the SCL-92, by item response analyses as compared with several previously reported factor analyses of this questionnaire in the literature. METHOD: The SCL-92 questionnaire was mailed to an age- and gender-stratified random sample of Danish citizens. The sample comprised 2040 individuals. The internal structure of the nine factors of the SCL-92 questionnaire was evaluated by Mokken-Loevinger analysis and Rasch analysis. RESULTS: In total, 1153 persons or 58% returned the questionnaire fully completed. Mokken analysis found all scales apart from the psychoticism scale acceptable. The Rasch analysis found most of the subscales to be robust. Minor problems were seen for the scales of phobic anxiety, obsession-compulsion and depression. Analysis of the Global Severity Index showed that the Rasch model was rejected for the full 92-item scale, but not for a scale consisting of the 63 items from the non-psychotic subscales. Spearman correlations among the subscales were all positive (range 0.34-0.79) and so were correlations between each of the subscales and the Global Severity Index (range 0.55-0.91). CONCLUSION: In this sample from the Danish general population the non-psychotic subscales, i.e. the subscales covering psychological distress were observed to function well. In a general population sample, the 63 non-psychotic items primarily appear to reflect one broad dimension of distress.

Humans↗

PubMed1991

Subject attrition in prevention research.

Subject attrition threatens the internal validity of substance abuse prevention studies because differences in the rate of attrition and the substance use behavior of remaining subjects in the different conditions could account for any differences found in substance use rates. Attrition threatens the external validity of prevention studies because, to the extent that study dropouts are different from remaining subjects, the results of the study may not be generalizable to study dropouts. Analysis of these threats to the validity of prevention studies should be routinely conducted. However, studies of alcohol and drug abuse prevention have generally failed to report or analyze subject attrition. Smoking prevention studies have more frequently reported attrition, and they have recently begun to analyze the degree to which attrition may affect the internal and external validity of the study. Evidence thus far suggests that differences in attrition across conditions do occur occasionally. The evidence is substantial that study dropouts are systematically more likely to smoke, to use other substances, and to score highly on other risk-taking measures.

Alcoholism↗

PubMed1976

Testing the internal and external validity of a simplified dental caries index on an adult population.

This analysis of a caries index, proposed in 1966 to WHO as a simplified method of measurement, as tested on a 16- to 45-year-old population who were seeking dental care at the University of Minnesota School of Dentistry revealed several weaknesses associated with the index. An analysis of the external validity of this index, a comparison with subjects' DMFS scores, revealed a correlation coefficient of 0.71. Although the index purports to measure the prevalence and severity of dental caries by dividing the dentition into five zones representing increasing severity of dental caries experience, an analysis of this index's internal validity, i.e. whether these five zones truly represent a rank-order scale of severity, revealed misclassification rates of from 21% for the total population up to 44% for a subgroup. When zones were recombined to reduce the misclassification rates, the descriptive capabilities of the index were greatly reduced as most subjects were then classified in only one or two of the zones.

Adolescent↗

PubMed2001

Reliability and validity of a modified Colorado Symptom Index in a national homeless sample.

This study examined the reliability and construct validity of a modified version of the Colorado Symptom Index (MCSI), a brief, self-report measure of psychological symptomatology, in a study of interventions to prevent homelessness. Eight projects in a national, cooperative study collected new data at baseline, 6, and 12 months using a set of common measures as well as site-specific instruments. The pooled sample consisted of 1,381 persons in treatment for mental illness or substance abuse (or both), of which 84% had a history of homelessness. The analyses employed classical and Rasch methods to examine the MCSI's content validity, internal consistency and item quality, test/retest reliability, dimensionality, appropriateness for the sample, construct validity, and responsiveness to change. This 14-item scale was found to be a reliable and valid measure of psychological symptoms in this sample. Its content was consistent with other symptom measures, its high internal consistency and test-retest coefficients supported its reliability, its relationships to other measures indicated that it had good construct validity, and it was responsive to change. We conclude that the MC

Adolescent↗

PubMedDate not supplied

Multinational validation of anxiety, hopelessness, and ineffective airway clearance.

The effective use of nursing diagnosis internationally depends in part on incorporating language and cultural difference into the common language of nursing. International validation studies can provide a basis for this effort. This study tested three diagnoses--anxiety, hopelessness, and ineffective airway clearance--through multinational validation. The Diagnostic Content Validity (DCV) model was used to collect data from critical care nurses in six countries. Defining characteristics rated as critical (greater than .80) by the total sample were dyspnea for ineffective airway clearance and panic and nervousness for anxiety. No critical defining characteristics for hopelessness were identified. DCV ratios for all defining characteristics are compared by country.

Airway Obstruction↗

PubMed2002

The Amsterdam preoperative anxiety and information scale provides a simple and reliable measure of preoperative anxiety.

PURPOSE: To compare three anxiety scales; the anxiety visual analogue scale (VAS), the anxiety component of the Amsterdam preoperative anxiety and information scale (APAIS), and the state portion of the Spielburger state-trait anxiety inventory (STAI), for assessment of preoperative anxiety levels in same day admission patients. METHODS: Patients completed the three anxiety assessment scales both before and after seeing the anesthesiologist preoperatively. The scales used were the STAI, the six-question APAIS, and the VAS. APAIS was further subdivided to assess anxiety about anesthesia (sum A), anxiety about surgery (sum S) and a combined anxiety total (i.e., sum C = sum A + sum S). These scales were compared to one another. Pearson's correlation (pair-wise deletion) was used for validity testing. Cronbach's alpha analysis was used to test internal validity of the various components of the APAIS scale. A correlation co-efficient (r) > or = 0.6 and P < 0.05 were considered significant. RESULTS: Four hundred and sixty three scale sets were completed by 197 patients. There was significant and positive correlation between VAS and STAI r = 0.64, P < 0.001), VAS and APAIS r = 0.6, P < 0.001), sum C and STAI r = 0.63, P < 0.001) and between VAS and sum C r = 0.61, P < 0.001). Sum C and STAI r value were consistent with repeated administration. Cronbach's alpha-levels for the anxiety components of the APAIS (sum C) and desire for information were 0.84 and 0.77 respectively. CONCLUSION: In addition to VAS, the anxiety component of APAIS (sum C) is a promising new practical tool to assess preoperative patient anxiety levels.

Adult↗

PubMed1993

The measurement of instrumental ADL: content validity and construct validity.

A new measure of Instrumental Activities of Daily Living (IADL), which is able to discriminate among the large group of elderly who do not depend on help, was tested for content validity and construct validity. Most assessments of functional ability include Physical ADL (PADL) and Instrumental ADL (IADL). PADL-scales assess the basic capacity of persons to care for themselves. IADL-scales are used to assess somewhat higher levels of performance, such as the ability to perform household chores or go shopping. Data were collected from 734 70-year-old people in Denmark in the county of Copenhagen. The measure of Instrumental ADL included 30 activities in relation to tiredness and reduced speed. Construct validity was tested by the Rasch model for item analysis; internal validity was specifically addressed by assessing the homogeneity of items under different conditions. The Rasch item analysis of IADL showed that 14 items could be combined into two qualitatively different additive scales. The IADL-measure complies with demands for content validity, distinguishes between what the elderly actually do, and what they are capable of doing, and is a good discriminator among the group of elderly persons who do not depend on help. It is also possible to add the items in a valid way. However, to obtain valid IADL-scales, we omitted items that were highly relevant to especially elderly women, such as house-work items. We conclude that the criteria employed for this IADL-measure are somewhat contradictory.

Activities of Daily Living↗

PubMed2005

Psychometric properties of the 15-item geriatric depression scale in functionally impaired, cognitively intact, community-dwelling elderly primary care patients.

OBJECTIVES: To examine the psychometric properties of the 15-item Geriatric Depression Scale (GDS-15), a brief depression screening measure. DESIGN: Cross-sectional. SETTING: Nineteen counties in western New York, West Virginia, and Ohio. PARTICIPANTS: Nine hundred sixty functionally impaired, cognitively intact, community-dwelling primary care patients aged 65 and older. MEASUREMENTS: The GDS-15, major depression as measured using the Mini-International Neuropsychiatric Interview, depressed mood, life satisfaction, suicidal ideation, and reported suicide attempts. RESULTS: Exploratory factor analyses suggested a two-factor structure for the GDS-15 in this category of patients, with component subscales assessing depression and positive affect. Cronbach alpha coefficients provide evidence for moderate, although acceptable, internal consistency reliability. Significant associations between the GDS-15 and measures of depressed mood, life satisfaction, and suicidal ideation demonstrated construct validity, whereas acceptable sensitivity and specificity to discriminate between depressed and nondepressed patients demonstrated criterion validity. Internal consistency reliability and construct validity did not differ significantly between patients with low and high functional impairment. A significant weakness of the scale is its low correlation with suicide attempt status. CONCLUSION: In general, this study provides evidence of impressive psychometric properties of the GDS-15 when administered to a sample of functionally impaired, cognitively intact, community-dwelling primary care patients.

Aged↗

PubMed2003

Validation of the ROSSMAX blood pressure measuring monitor according to the European Society of Hypertension International Protocol for Validation of Blood Pressure Measuring Devices in Adults.

BACKGROUND: It is now accepted that blood pressure measuring devices should be subjected to an independent evaluation of their accuracy before they are marketed for clinical use. The results of validation of the ROSSMAX Blood Pressure Measuring Monitor for self-measurement according to the European Society of Hypertension International Protocol for Validation of Blood Pressure Measuring Devices in Adults are presented in this paper. POPULATION: Thirty-three subjects were recruited from among staff and patients at Beaumont Hospital, Dublin, Ireland. METHODS: The ROSSMAX monitor was connected to the Sphygmocorder, an audiovisual system for validation, which records blood pressure on tape and video for later analysis. Nine sequential same-arm measurements between the device and a standard mercury sphygmomanometer were recorded using the Sphygmocorder. RESULTS: In phase 1, the ROSSMAX monitor produced 21 measurements within 5 mmHg, 31 within 10 mmHg and 38 within 15 mmHg for systolic blood pressure (SBP), and 36 within 5 mmHg, 43 within 10 mmHg and 45 within 15 mmHg for diastolic blood pressure (DBP). The mean differences were -5.6 (10.2) [mean (SD)] mmHg for SBP and -0.5 (4.5) mmHg for DBP. The ROSSMAX monitor failed to meet any of the criteria for SBP but comfortably passed all of the criteria for DBP. In phase 2.1, the ROSSMAX monitor had 51 measurements within 5 mmHg, 73 within 10 mmHg and 86 within 15 mmHg for SBP, and 71 measurements within 5 mmHg, 93 within 10 mmHg and 98 within 15 mmHg for DBP. The mean differences were -4.5. (9.5) mmHg for SBP and -1.8 (5.0) mmHg for DBP. The ROSSMAX monitor failed to meet any of the criteria for SBP but comfortably passed all of the criteria for DBP. In phase 2.2, 16 subjects had at least two of the differences lying within 5 mmHg and 10 subjects had no differences within 5 mmHg for SBP; 26 subjects had at least two of the differences falling within 5 mmHg and three subjects no differences within 5 mmHg for DBP. The ROSSMAX monitor failed to meet the criteria for SBP but passed the criteria for DBP. CONCLUSIONS: The ROSSMAX monitor cannot be recommended for clinical use in an adult population because it records SBP inaccurately.

Adult↗

PubMed1992

Analysis of randomized and nonrandomized patients in clinical trials using the comprehensive cohort follow-up study design.

In clinical research, randomized trials are widely accepted as the definitive method of evaluating the efficacy of therapies. The random assignment of patients to their treatment ensures the internal validity of the comparison of new treatments with controls. An assessment of the external validity of trial results can best be achieved by comparing the study population to the population of patients who met the eligibility criteria but did not consent to randomization. A part of the data of the Coronary Artery Surgery Study (CASS), in which coronary artery bypass surgery is compared to conventional medical therapy in patients with coronary artery disease, is used to illustrate a strategy of multivariate analysis of randomized and nonrandomized patients which allows an investigation of both internal and external validity. The method used Cox's proportional hazards regression model with inclusion of covariates for randomization status and corresponding interactions in addition to the usual covariates for treatment and the important prognostic factors.

Cohort Studies↗

PubMed1997

Brief report: cross-validation of the Injury Behavior Checklist in a school-age sample.

Examined descriptive characteristics, internal validity, and convergent validity of the Injury Behavior Checklist (IBC) in a sample of 7- to 10-year-old children. Although the IBC was originally designed for use with preschool children, results of the present study showed that it has acceptable psychometric qualities for use with children as old as 9 years. The IBC shows promise as an easily administered instrument for research on psychological and behavioral mechanisms of childhood injury, as well as for individual screening for injury liability.

Child↗

PubMed1993

The side effects of antipsychotic drugs and patients' quality of life: patient education and preference assessment with computers and multimedia.

Determining the relative value of novel antipsychotics such as clozapine requires measures of the utility of their different side-effect profiles. Many of these side effects (SE) are complex and difficult to describe adequately. Schizophrenic patients are also difficult to interview reliably. Even in normal subjects, utility assessment can be tedious, inconsistent, and difficult for subjects to understand. We addressed these challenges by developing a multimedia patient education and utility assessment tool. SE were described using short video sequences accompanied by digitized voice descriptions. Patients' preferences were assessed using visual analog scales, pairwise comparisons, and standard gambles. These assessment techniques were carefully explained and logically integrated. Instructions were presented both by digitized voice and in print, and, if necessary, were clarified by a moderator. Animated displays were used to graphically display probability. Reminder pictures, comprehension tests and validation questions were used throughout the survey. Thirty-three patients from VA and public clinic inpatient and outpatient settings took the survey. Five psychiatrists were surveyed as a reference group. Patients understood the SE and the survey (92% mean comprehension) and their answers were internally valid and consistent (74% internal consistency). The standard gamble disutilities for the SE were substantial, ranging from 12-20% decrease in their quality of life. Computer-based, multimedia techniques are useful in conducting utility assessment and evaluating its validity. They allow effective patient education and elicitation of useful values, even in subjects with cognitive impairments.

Adult↗

PubMedDate not supplied

Customization of pain treatments: single-case design and analysis.

The aim of this paper is to acquaint pain researchers and practitioners with recent developments in the single-case experimental approach and their potential to allow for tailoring the treatment and its evaluation to the specific complaints, aptitudes, or profile of the individual patient, without violating the canons of good science and practice. After contrasting the single-case experimental approach and the case-study approach, we show the possibilities of customization in design, measurement, and test statistics. This is done by distinguishing 2 types of single-case designs--alternation designs and phase designs--and 2 types of replication strategies--simultaneous replications and sequential replications. In addition, tailor-made randomization tests are proposed for alternation, phase, and simultaneous replication designs and the combining of P values to perform a meta-analysis on designs that are sequentially replicated. With our emphasis on: 1) randomization in the design; 2) the possibilities for a statistical test (together with the determination of power and the calculation of effect sizes); 3) the importance of reliable and valid measurement; and 4) the role of replication, we demonstrate how internal validity, statistical-conclusion validity, construct validity, and external validity concerns can be dealt with within a single-case experimental approach framework. Finally, the many research examples and references to clinical work illustrate the usefulness of the approach.

Data Interpretation, Statistical↗

PubMed2005

The clinical and cost-effectiveness of implantable cardioverter defibrillators: a systematic review.

OBJECTIVES: To consider the clinical effectiveness and cost-effectiveness of implantable cardioverter defibrillators (ICDs) for arrhythmias. DATA SOURCES: Electronic databases. Manufacturer submissions. REVIEW METHODS: A systematic review of the literature on clinical and cost-effectiveness was undertaken. The quality of selected randomised controlled trials (RCTs) was assessed using the Jadad criteria, and of selected systematic reviews using criteria developed by the NHS Centre for Reviews and Dissemination. Economic evaluations were quality assessed by their internal validity (i.e. the methods used) using a series of relevant questions, and external validity (i.e. generalisability of the economic study to the population of interest) by modified standard criteria. The clinical effectiveness and cost-effectiveness of ICDs for arrhythmias were synthesised through a narrative review with full tabulation of results of all included studies. RESULTS: Eight RCTs, two systematic reviews and a meta-analysis met the inclusion criteria of the review. The RCTs were of variable quality, with most trials having a Jadad quality score of 1/5 or 2/5, owing to the nature of comparing a device with drug therapy and the impossibility of double-blinding. The outcome measure of interest was mortality, which was reported as all-cause mortality in most trials and sudden cardiac death in some trials. Eleven economic evaluations of ICDs for arrhythmias were identified. None were shown to have high internal and external validity. One unpublished study relevant to the UK was identified. The evidence suggests that ICDs reduce mortality in patients with previous ventricular arrest or symptomatic sustained ventricular arrhythmias, in patients who have not had a previous sudden cardiac episode or previous ventricular arrhythmia but have reduced left ventricular function due to coronary artery disease with asymptomatic non-sustained ventricular arrhythmia and sustained tachycardia that could be induced electrophysiologically, and in some patients with severe left ventricular dysfunction (ejection fraction 30%) after myocardial infarction. QoL data are inconsistent but suggest that there is impaired QoL in patients who received numerous shocks from implanted devices. Studies show that ICDs improve survival compared with drug treatment, but with considerably increased cost. Incremental cost per life-year gained ranges from 27,000 US dollars to 213,543 Can dollars and incremental cost per quality-adjusted life-year from 71,700 US dollars to 558,000 US dollars in the published literature. CONCLUSIONS: The use of ICDs in the UK is increasing, but the technology is still under-utilised compared with other developed countries. Extending the current indications to patients with prior myocardial infarction and depressed heart function would impact on costs and service provision. Further research is needed on the risk stratification of patients in whom ICDs are most likely to be clinically and cost-effective. An evaluation of shock frequency on QoL is also required.

Aged↗