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PubMed2005

Multiple Mantel tests and isolation-by-distance, taking into account long-term historical divergence.

Mantel tests of matrix correspondence have been widely used in population genetics to examine microevolutionary processes, such as isolation-by-distance (IBD). We used partial and multiple Mantel tests to simultaneously test long-term historical effects and current divergence and equilibrium processes, such as IBD. We used these procedures to calculate genetic divergence among Eugenia dysenterica (Myrtaceae) populations in Central Brazil. The Nei's genetic distances between pairs of local populations were strongly correlated with geographic distances, suggesting an IBD process, but field observations and the geographic distribution of the samples suggest that populations may have been subjected to more complex evolutionary processes of genetic divergence. Partial Mantel regression was used to partition the effects of geographic structure and long-term divergence associated with a possible historical barrier. The R(2) of the model with both effects was 73.3%, and after the partition 21.9% of the variation in the genetic distances could be attributed to long-term historical divergence alone, whereas only 1.5% of the variation in genetic distances could be attributed to IBD. As expected, there was a large overlap between these processes when explaining genetic divergence, so it was not possible to entirely partition divergence between historical and contemporary processes.

Biological Evolution↗

PubMed1994

[A written clinical multiple choice test for certain groups of foreign physicians].

The Faculty of Medicine, University of Oslo, advises the health authorities with respect to judging the qualifications of foreign physicians applying for authorization in Norway. In 1988 the Faculty introduced a medical multiple choice test covering nine clinical subjects for physicians with a degree from countries outside Western Europe and USA/Canada. The authors present experiences from 123 examinations during the first four years the test was used. The mean percentage failure was 33, compared with five and six respectively in the control study among a random sample of Norwegian medical specialists and medical students in the final part of their studies. It is concluded that the constructed test fulfills its intention, namely to represent a reasonably fair and suitable method for judging clinical knowledge.

Clinical Competence↗

PubMed2005

The Multiple Tasks Test as a predictor of falls in older adults.

PURPOSE: Falls are among the most common and serious problems facing the elderly. The Berg Balance Scale (BBS) is the gold standard in measuring falls risk. With higher functioning elders, a ceiling effect is often evidenced using the BBS. The purpose of this study was to determine if the Multiple Tasks Test (MTT) when used in high functioning community dwelling elderly correlated with the BBS. Secondly, this study assessed the unidimensionality of the MTT. If a relationship existed between the performance of multiple tasks and the potential loss of balance resulting in falls, then the MTT would be more appropriate than the BBS at predicting falls in higher functioning individuals. METHODS: Twenty-two independent community dwelling older adults were tested using both the MTT and the BBS on the same day at a senior center. DATA ANALYSIS: Correlations between the BBS and the MTT ranged between -0.765 and -0.79. The results of the Guttman's scalability analysis were a plus percentage ratio of 0.75 and an index of reproducibility of 0.93. Scales with these values are regarded as having evidence of unidimensionality. SUMMARY: All of the MTT tests correlated with the BBS. In addition, the MTT was found to be unidimensional. CONCLUSION: Although the MTT correlated with the BBS and was found to be a good cumulative measure, it would benefit from continued study to examine quantifiability, validity and reliability. With further refinement and study, the MTT may be useful at discriminating fallers from non-fallers in high functioning older adults.

Accidental Falls↗

PubMed2003

Controlling the familywise error rate in functional neuroimaging: a comparative review.

Functional neuroimaging data embodies a massive multiple testing problem, where 100,000 correlated test statistics must be assessed. The familywise error rate, the chance of any false positives is the standard measure of Type I errors in multiple testing. In this paper we review and evaluate three approaches to thresholding images of test statistics: Bonferroni, random field and the permutation test. Owing to recent developments, improved Bonferroni procedures, such as Hochberg's methods, are now applicable to dependent data. Continuous random field methods use the smoothness of the image to adapt to the severity of the multiple testing problem. Also, increased computing power has made both permutation and bootstrap methods applicable to functional neuroimaging. We evaluate these approaches on t images using simulations and a collection of real datasets. We find that Bonferroni-related tests offer little improvement over Bonferroni, while the permutation method offers substantial improvement over the random field method for low smoothness and low degrees of freedom. We also show the limitations of trying to find an equivalent number of independent tests for an image of correlated test statistics.

Brain↗

PubMed2005

In vitro allergy investigation: Does a multiple allergen testing system give useful information?

INTRODUCTION: The Hitachi CLA allergy test gives individual results on a wide range of common allergens. This study looked at the effect on patient management of the extra information gleaned from the use of this test compared to the same patient being investigated under a protocol of a total IgE and 4 allergen specific IgE tests using the Pharmacia UNICAP system. DESIGN, SETTING AND PATIENTS: Fifty-four patients who presented to our Dermatology Department with possible Type I hypersensitivity: 19 males (10 were <16 years); 36 females (12 were <16 years). Our standard investigative protocol using the Pharmacia UNICAP was applied to all samples; each was also tested using the Hitachi CLA system and the two sets of data compared. RESULTS: The CLA system identified 22/54 patients in which one or more potentially significant allergens were found that would not have been identified by our current system of total IgE plus 4 allergen specific IgE results. Multiple positive allergens were detected by the CLA system in 13/54 cases. 12/54 patients had no allergen that was positive CLA and the UNICAP. 3/54 had positive results using our Pharmacia-based protocol that were not available by use of the extended panel. 4/54 patients had profiles in which both systems offered differing clinically useful information. CONCLUSION: These data support the use of a multiple allergen testing system to identify potentially significant individual allergens, patients in whom a Type I allergic reaction is unlikely or patients with multiple positive results for whom allergen avoidance is unlikely to be effective.

Adult↗

PubMed2001

A multiple-station test of the teaching skills of general practice preceptors in Flanders, Belgium.

PURPOSE: The Interuniversity Center for Education in General Practice in Flanders, Belgium, supervises its general practice (GP) preceptors so they will meet the quality criteria required for their role in training general practitioners. The author developed a teaching skills assessment test to determine the individual preceptors' competence regarding teaching. The preliminary research described in this article, carried out in 1999, aimed to verify the reliability, validity, and acceptability of that multiple-station test. METHOD: The test consists of seven stations in which simulated teaching situations are portrayed. In the present study, in each station, the GP preceptors (n = 35) had a learning conversation with a standardized GP trainee. The teaching situations were (1) drawing up a learning agenda, (2) leading an advisory conversation, (3) having an exchange of information about practice visits, (4) having a case-related discussion, (5) having a feedback conversation, (6) giving a demonstration of a particular skill or technique, and (7) having an intermediate evaluation conversation. In each station two observers independently scored the preceptors on a five-point scale. RESULTS: The preceptors' scores on the entire test ranged from 30 to 82.7 on a scale whose maximum was 100. The average score was 54.4 (SD, 11.6), and the average scores on the various stations fluctuated between 51.2 and 57.7. The interobserver reliability varied from good to very good for five of the seven stations (Pearson r = 0.77-0.92). The separate stations had a good internal consistency (Cronbach alpha = 0.85). Based on these research results only, the content validity and acceptability of the instrument are good for the GP preceptors in Flanders. CONCLUSIONS: The study findings suggest that the teaching skills assessment test is a reliable instrument, especially fit for screening GP preceptors' teaching skills. However, validation of the instrument needs further investigation.

Belgium↗

PubMed2006

Multiple balance tests improve the assessment of postural stability in subjects with Parkinson's disease.

OBJECTIVES: Clinicians often base the implementation of therapies on the presence of postural instability in subjects with Parkinson's disease (PD). These decisions are frequently based on the pull test from the Unified Parkinson's Disease Rating Scale (UPDRS). We sought to determine whether combining the pull test, the one-leg stance test, the functional reach test, and UPDRS items 27-29 (arise from chair, posture, and gait) predicts balance confidence and falling better than any test alone. METHODS: The study included 67 subjects with PD. Subjects performed the one-leg stance test, the functional reach test, and the UPDRS motor exam. Subjects also responded to the Activities-specific Balance Confidence (ABC) scale and reported how many times they fell during the previous year. Regression models determined the combination of tests that optimally predicted mean ABC scores or categorised fall frequency. RESULTS: When all tests were included in a stepwise linear regression, only gait (UPDRS item 29), the pull test (UPDRS item 30), and the one-leg stance test, in combination, represented significant predictor variables for mean ABC scores (r2 = 0.51). A multinomial logistic regression model including the one-leg stance test and gait represented the model with the fewest significant predictor variables that correctly identified the most subjects as fallers or non-fallers (85% of subjects were correctly identified). CONCLUSIONS: Multiple balance tests (including the one-leg stance test, and the gait and pull test items of the UPDRS) that assess different types of postural stress provide an optimal assessment of postural stability in subjects with PD.

Accidental Falls↗

PubMed1997

[Use of multiple-choice tests in medical education].

The actual state of the is connected some problems. The rules for the creation tests from the viewpoint of logics of questions and formal structure are mostly not respected. The mentioned rules are prepared in the field of theoretical pedagogics, but did not entered until now enough in the medical education. The result is the lower relevance of the tests in terms of their validity and reliability. In the paper is presented the set of principles for the correct structure of questions and in the same time the classification of the multiple-choice tests with the rules of their creation.

Education, Medical↗

PubMed2005

Probing the primary screening efficiency by multiple replicate testing: a quantitative analysis of hit confirmation and false screening results of a biochemical assay.

Despite a large body of references on assay development, assay optimization, strategies, and methodologies for high-throughput screening (HTS), there have been few reports on investigations of the efficiency of primary screening in a systematic and quantitative manner for a typical HTS process. Recently, the authors investigated the primary hit comparison and the effect of measurement variability by screening a library of approximately 25,000 random compounds in multiple replicate tests in a nuclear receptor recruitment assay with 2 different assay detection technologies. In this report, we utilized these sets of multiple replicate screening data from a different perspective and conducted a systematic data analysis in order to gain some insights into the hit-finding efficiency of a typical primary screening process. Specifically, hit confirmation, false-positive (declaration) rates, and false-negative rates at different hit cutoff limits were explored and calculated from the 2 different assay formats. Results and analyses provided some quantitative estimation regarding the reliability and efficiency of the primary screening process. For the 2 assay formats tested in this report, the confirmation rate (activity repeated at or above a certain hit limit) was found to be 65% or above. It was also suggested that, at least in this case, applying some hit-selection strategies, it is possible to decrease the number of false-negative or false-positive hits without significantly increasing the efforts in primary screening.

DNA-Binding Proteins↗

PubMed2006

Hypermnesia and total retrieval time.

Recall performance sometimes improves over repeated recall attempts, a phenomenon dubbed hypermnesia. A critical theoretical issue is whether hypermnesia is due to repeated testing per se or increased retrieval time. The present experiments investigated by contrasting five testing conditions. All participants were presented with the same study list followed by either two shorter recall tests or a single longer test. In the multiple test conditions, the tests were either separated by a (filled) 7-minute interval (the multiple-split condition), or presented consecutively, with no break (the multiple-immediate condition). In the single test conditions, the test either began at the start of the recall session, after a (filled) 7-minute delay, or with a 7-minute interruption inserted in the middle. The multiple-split condition produced more reminiscence and hypermnesia than the multiple-immediate condition. More importantly, the multiple-split condition produced greater cumulative recall than any of the other conditions (which did not differ among themselves). That is, single and repeated recall tests of equal total duration are not functionally equivalent.

Amnesia↗

PubMed1981

The electrophoretic demonstration of unique oligoclonal immunoglobulins in cerebrospinal fluid as a diagnostic test for multiple sclerosis.

Polyacrylamide disc gel electrophoresis was performed on unconcentrated cerebrospinal fluid and serum from 132 neurological patients and from 33 patients without neurological disease. The presence of unique, discrete immunoglobulin bands in the gamma-globulin (cathodal) region of the cerebrospinal fluid gel was assessed as a diagnostic test for multiple sclerosis. The procedure exhibited a specificity for multiple sclerosis of 94% and a sensitivity of 72%, and is easier to perform than most of the other published procedures used to demonstrate oligoclonal immunoglobulins in cerebrospinal fluid. It is recommended for use in the clinical chemistry laboratory as a valuable adjunct to the diagnosis of multiple sclerosis.

Humans↗

PubMed1998

Is the Beck Depression Inventory reliable over time? An evaluation of multiple test-retest reliability in a nonclinical college student sample.

The Beck Depression Inventory (BDI) is one of the most widely used measures of depression. Many studies have examined the reliability and validity of the BDI. However, we found no published studies that considered the stability of the BDI over multiple administrations (i.e., more than 3 trials), such as is common in clinical trials research and during some clinical interventions. The purpose of this study is to examine the multiple test-retest reliability of the BDI in a presumably nonclinical sample. Results show a 40% decline in BDI scores over 8 weeks, a main effect that accounts for approximately 10% of the variance. We achieved a 40% decrease in self-reported symptoms of depression due to repeated measurement alone, not due to any intervention. This change likely represents measurement error with this instrument rather than any "real" change in depression. The limitations of this study, its implications for research, and its applications to clinical practice are discussed.

Adult↗

PubMed2000

Perceptual interference at encoding enhances item-specific encoding and disrupts relational encoding: evidence from multiple recall tests.

Interfering with perception during encoding can enhance later memory, a phenomenon known as the perceptual interference effect. This effect is investigated in the context of the item-specific-relational framework (e.g., Hunt & McDaniel, 1993), which suggests that the perceptual interference enhances item-specific encoding and impedes relational encoding. Two experiments performed with multiple recall tests support this view. Prior research indicates that item-specific processing increases item gains across tests, whereas relational processing protects against item losses (e.g., Burns, 1993; Klein, Loftus, Kihlstrom, & Aseron, 1989). Consistent with the item-specific-relational framework, perceptual interference produced significant increases in both item gains and losses relative to a control condition.

Adult↗

PubMed2004

Outcome of pregnancy in homozygous sickle cell disease.

OBJECTIVE: Previous reports on pregnancy in homozygous sickle cell (SS) disease are biased by hospital-based, more severely affected subjects and may have underestimated recurrent early pregnancy losses. We report pregnancy outcome in a representative sample of SS subjects subsequently referred to as "subjects" or "sickle cell subjects," and matched normal controls followed from birth. METHODS: The outcomes of 94 pregnancies in 52 subjects and 157 pregnancies in 68 controls followed in a cohort study from birth are presented. Outcome measures included the age at menarche, interval to first pregnancy, outcome of pregnancy, and maternal complications. Possible predictors of low birth weight are assessed. Outcomes were compared by the Kaplan-Meier analysis for interval to first pregnancy and by Student t test, chi(2) test, or Fisher exact test, as appropriate. Correction was made for multiple testing, and multiple linear regression was used for analysis of birth weight. RESULTS: Compared with controls, SS subjects had later menarche (median age 15.4 versus 13.0 years) and first pregnancy (median age 23.7 versus 20.1 years), and more spontaneous abortions (36% versus 10%). Babies of SS subjects had a lower gestational age (P <.001) and lower birth weight (P <.001), the latter being significantly affected by sickle-related events in pregnancy. There was no difference in pregnancy-induced hypertension, preeclampsia, or antepartum or postpartum hemorrhage, but a retained placenta was marginally more common in SS subjects (Fisher exact test, P =.007 after adjustment for multiple testing). Two SS subjects died, a mortality rate of 2.1%. CONCLUSION: The increased fetal loss and maternal morbidity in mothers with homozygous sickle cell disease is confirmed. LEVEL OF EVIDENCE: II-2

Abortion, Spontaneous↗

PubMed2004

Randomized, double-blinded, placebo-controlled trial of intravenously administered hyoscine N-butyl bromide in patients undergoing colonoscopy with patient-controlled sedation.

BACKGROUND: A prospective, double-blinded, placebo-controlled randomized trial was conducted to investigate the effect of the antispasmodic hyoscine N-butyl bromide (Buscopan) during colonoscopy. METHODS: A total of 120 patients undergoing colonoscopy were randomized to receive either 40 mg of hyoscine N-butyl bromide (n=60) or normal saline solution (n=60) intravenously as premedication. Colonoscopy was performed under patient-controlled sedation. Outcome measures included cecal intubation and total procedure time, demanded and administered doses of patient-controlled sedation, spasm score, pain score, endoscopist satisfaction score, patient willingness to repeat colonoscopy, and vital signs (blood pressure, pulse rate) during colonoscopy. RESULTS: Mean cecal intubation time in the hyoscine N-butyl bromide group was significantly longer than the control group (12.20 vs. 9.74 minutes; p=0.04; but correction for multiple testing of data removed this significance). The use of hyoscine N-butyl bromide was associated with a significantly lower endoscopist mean satisfaction score (6.47 vs. 7.30; p=0.04; but correction for multiple testing of data removed this significance), higher demanded and administered mean doses of patient-controlled sedation (respectively, 34.80 and 7.25 vs. 24.20 and 5.87; p=0.045; p=0.04, respectively; but correction for multiple testing of data removed these findings of significance), fewer patients willing to repeat colonoscopy (60% vs. 83.9%; p=0.005), and more hemodynamic instability (p<0.001) when compared with the control group. No significant difference was found in the total procedure time, spasm score, or pain score. CONCLUSIONS: Premedication with intravenously administered hyoscine N-butyl bromide impedes colonoscope insertion and causes greater patient discomfort, as well as hemodynamic instability.

Adult↗

PubMed2001

Evaluation of protein multiple alignments by SAM-T99 using the BAliBASE multiple alignment test set.

MOTIVATION: SAM-T99 is an iterative hidden Markov model-based method for finding proteins similar to a single target sequence and aligning them. One of its main uses is to produce multiple alignments of homologs of the target sequence. Previous tests of SAM-T99 and its predecessors have concentrated on the quality of the searches performed, not on the quality of the multiple alignment. In this paper we report on tests of multiple alignment quality, comparing SAM-T99 to the standard multiple aligner, CLUSTALW. RESULTS: The paper evaluates the multiple-alignment aspect of the SAM-T99 protocol, using the BAliBASE benchmark alignment database. On these benchmarks, SAM-T99 is comparable in accuracy with ClustalW. AVAILABILITY: The SAM-T99 protocol can be run on the web at http://www.cse.ucsc.edu/research/compbio/HMM-apps/T99-query.html and the alignment tune-up option described here can be run at http://www.cse.ucsc.edu/research/compbio/HMM-apps/T99-tuneup.html. The protocol is also part of the standard SAM suite of tools. http://www.cse.ucsc.edu/research/compbio/sam/

Computational Biology↗

PubMed2000

Results of multiple diagnostic tests for Mycobacterium avium subsp. paratuberculosis in patients with inflammatory bowel disease and in controls.

Mycobacterium avium subsp. paratuberculosis has been incriminated as a cause of Crohn's disease (CD); however, studies to date have been relatively small and generally only used a single diagnostic assay. The objective of the study was to reexamine the association of M. avium subsp. paratuberculosis and CD using multiple diagnostic tests. Five methods were used to detect M. avium subsp. paratuberculosis infections in 439 inflammatory bowel disease (IBD) patients and 324 control subjects in the United States and Denmark. Most assays were adaptations of diagnostic tests for this infection performed routinely on animals. PCR for IS900, a genetic element unique to M. avium subsp. paratuberculosis, was positive significantly more often on resected bowel and lymph node tissues from CD patients (19.0%) and ulcerative colitis (UC) patients (26.2%) than from controls (6. 3%) (P < 0.05). Positive IS900 PCR results occurred more often in U. S. than in Danish IBD patients, 32.0 versus 13.3% (P = 0.025). The majority of Danish patients were bacillus Calmette-Guérin (Mycobacterium bovis BCG) vaccinated (CD, 77.5%; UC, 86.6%; controls, 83.0%) whereas none of the U.S. patients with IBD and only 2% of U. S. controls were vaccinated. Among Danish IBD patients, positive PCR findings were four times more common among subjects who were not BCG vaccinated (33.3%) than among BCG vaccinates (8.8%, P = 0.02). Culture of the same tissues tested by PCR using modified BACTEC 12B medium failed to grow M. avium subsp. paratuberculosis from patients or controls. U.S. CD patients had the highest serological evidence (enzyme-linked immunosorbent assay [ELISA] for serum antibodies) of M. avium subsp. paratuberculosis infection (20.7% of patients positive) which was higher than for all UC patients studied (6.1%) or healthy controls (3.8%, P < 0.005). Among Danish patients alone, however, no significant differences in rates of ELISA-positive results among CD, UC, or control patients were found. For 181 study subjects, both IS900 PCR and ELISA were performed. Although 11 were ELISA positive and 36 were PCR positive, in no instance was a patient positive by both tests, suggesting that these states are mutually exclusive. Evaluation of cytokine-mediated immune responses of IBD patients was complicated by the influence of immunosuppressive therapy given most IBD patients. Gamma interferon (IFN-gamma) release by peripheral blood leukocytes after M. avium purified protein derivative PPD antigen stimulation showed significantly lower responses in CD patients than in UC patients or controls in both U.S. (by ex vivo assay) and Danish (by in vitro assay) populations (P < 0.05). Interleukin-5 responses were not different among CD, UC, or control groups. Collectively, the PCR, ELISA, and IFN-gamma tests for M. avium subsp. paratuberculosis together with the unexpected observation that BCG vaccination influenced M. avium subsp. paratuberculosis detection, lead us to conclude that M. avium subsp. paratuberculosis, or some similarly fastidious mycobacterial species, infects at least a subset of IBD patients. Whether the infection is primary (causal) or secondary, it may contribute to the etiopathogenesis of IBD.

Adult↗

PubMed1986

Accuracy of standard urinalysis in predicting culture results.

Single and multiple test combinations were studied to determine the accuracy of the standard urinalysis method in predicting sterile or contaminated cultures and cultures with significant bacteriuria from gram negative rods (GNR). The results demonstrated a significant incidence of microscopic bacteriuria and pyuria in GNR culture (P < .001) and an association between large numbers of epithelial cells and culture contamination. A discriminate analysis of multiple test combinations was done to identify the order in which urinalysis tests significantly improved the ability to discriminate between culture groups. Results indicated that multiple test combinations were more predictive than single tests. Based on study results, a cost-effective scheme for ordering urine cultures is proposed.

Bacteriological Techniques↗