Displaying publications 1 - 20 of 65 in total

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  1. Zero-inflated Conway-Maxwell Poisson Distribution to Analyze Discrete Data
    Sim SZ, Gupta RC, Ong SH
    Int J Biostat, 2018 Jan 09;14(1).
    PMID: 29306919 DOI: 10.1515/ijb-2016-0070
    In this paper, we study the zero-inflated Conway-Maxwell Poisson (ZICMP) distribution and develop a regression model. Score and likelihood ratio tests are also implemented for testing the inflation/deflation parameter. Simulation studies are carried out to examine the performance of these tests. A data example is presented to illustrate the concepts. In this example, the proposed model is compared to the well-known zero-inflated Poisson (ZIP) and the zero- inflated generalized Poisson (ZIGP) regression models. It is shown that the fit by ZICMP is comparable or better than these models.
    Matched MeSH terms: Data Interpretation, Statistical*
  2. Fulltext Wrong conclusion when the statistical test is incorrect
    Norsa'adah B
    Med J Malaysia, 2004 Dec;59(5):692; author reply 693-5.
    PMID: 15889579
    Matched MeSH terms: Data Interpretation, Statistical*
  3. Thermal distribution analysis of three-dimensional tumor-embedded breast models with different breast density compositions
    Wahab AA, Salim MI, Ahamat MA, Manaf NA, Yunus J, Lai KW
    Med Biol Eng Comput, 2016 Sep;54(9):1363-73.
    PMID: 26463520 DOI: 10.1007/s11517-015-1403-7
    Breast cancer is the most common cancer among women globally, and the number of young women diagnosed with this disease is gradually increasing over the years. Mammography is the current gold-standard technique although it is known to be less sensitive in detecting tumors in woman with dense breast tissue. Detecting an early-stage tumor in young women is very crucial for better survival chance and treatment. The thermography technique has the capability to provide an additional functional information on physiological changes to mammography by describing thermal and vascular properties of the tissues. Studies on breast thermography have been carried out to improve the accuracy level of the thermography technique in various perspectives. However, the limitation of gathering women affected by cancer in different age groups had necessitated this comprehensive study which is aimed to investigate the effect of different density levels on the surface temperature distribution profile of the breast models. These models, namely extremely dense (ED), heterogeneously dense (HD), scattered fibroglandular (SF), and predominantly fatty (PF), with embedded tumors were developed using the finite element method. A conventional Pennes' bioheat model was used to perform the numerical simulation on different case studies, and the results obtained were then compared using a hypothesis statistical analysis method to the reference breast model developed previously. The results obtained show that ED, SF, and PF breast models had significant mean differences in surface temperature profile with a p value <0.025, while HD breast model data pair agreed with the null hypothesis formulated due to the comparable tissue composition percentage to the reference model. The findings suggested that various breast density levels should be considered as a contributing factor to the surface thermal distribution profile alteration in both breast cancer detection and analysis when using the thermography technique.
    Matched MeSH terms: Data Interpretation, Statistical
  4. The relationship of hostility, negative affect and ethnicity to cardiovascular responses: an ambulatory study in Singapore
    Enkelmann HC, Bishop GD, Tong EM, Diong SM, Why YP, Khader M, et al.
    Int J Psychophysiol, 2005 May;56(2):185-97.
    PMID: 15804452
    This study tested the hypotheses that ambulatory heart rate and blood pressure would be higher for individuals high but not low in hostility when they experienced negative affect or social stress and that this interaction would be stronger for Indians compared with other Singapore ethnic groups. Ambulatory blood pressure monitoring was done on 108 male Singapore patrol officers as they went about their daily duties. After each BP measurement participants completed a computerized questionnaire including items on emotional experience. Individuals high in hostility showed higher systolic blood pressure when reporting negative affect whereas this was not true for those low in hostility. Ethnic differences were obtained such that Indians showed an increase in mean arterial pressure when angered whereas MAP was negatively related to anger for Malays and unrelated for Chinese. Also a three-way interaction between ethnicity, hostility, and social stress indicated that hostility and social stress interacted in their effects on DBP for Indian participants but not for Chinese or Malays. Finally, a three-way interaction was obtained between ethnicity, hostility and negative affect for heart rate in which heart rate increased with increasing levels of negative affect for Chinese high in hostility and Malays low in hostility but decreased with increasing negative affect for all other participants. These data are consistent with higher CHD rates among individuals high in hostility and also provide additional evidence on ethnic differences in cardiovascular reactivity in Singapore.
    Matched MeSH terms: Data Interpretation, Statistical
  5. The performance of multiple imputations for different number of imputations
    Ser G, Keskin S, Can Yilmaz M
    Sains Malaysiana, 2016;45:1755-1761.
    Multiple imputation method is a widely used method in missing data analysis. The method consists of a three-stage
    process including imputation, analyzing and pooling. The number of imputations to be selected in the imputation step
    in the first stage is important. Hence, this study aimed to examine the performance of multiple imputation method at
    different numbers of imputations. Monotone missing data pattern was created in the study by deleting approximately 24%
    of the observations from the continuous result variable with complete data. At the first stage of the multiple imputation
    method, monotone regression imputation at different numbers of imputations (m=3, 5, 10 and 50) was performed. In the
    second stage, parameter estimations and their standard errors were obtained by applying general linear model to each
    of the complete data sets obtained. In the final stage, the obtained results were pooled and the effect of the numbers of
    imputations on parameter estimations and their standard errors were evaluated on the basis of these results. In conclusion,
    efficiency of parameter estimations at the number of imputation m=50 was determined as about 99%. Hence, at the
    determined missing observation rate, increase was determined in efficiency and performance of the multiple imputation
    method as the number of imputations increased.
    Matched MeSH terms: Data Interpretation, Statistical
  6. Testing the agreement of medical instruments: overestimation of bias in the Bland-Altman analysis
    Zaki R, Bulgiba A, Ismail NA
    Prev Med, 2013;57 Suppl:S80-2.
    PMID: 23313586 DOI: 10.1016/j.ypmed.2013.01.003
    The Bland-Altman method is the most popular method used to assess the agreement of medical instruments. The main concern about this method is the presence of proportional bias. The slope of the regression line fitted to the Bland-Altman plot should be tested to exclude proportional bias. The aim of this study was to determine whether the overestimation of bias in the Bland-Altman analysis is still present even when the proportional bias has been excluded.
    Matched MeSH terms: Data Interpretation, Statistical
  7. Statistical process control tools for monitoring clinical performance
    Lim TO
    Int J Qual Health Care, 2003 Feb;15(1):3-4.
    PMID: 12630794 DOI: 10.1093/intqhc/15.1.3
    Matched MeSH terms: Data Interpretation, Statistical*
  8. Fulltext Statistical analysis plan for the 'Tranexamic acid for hyperacute primary IntraCerebral Haemorrhage' (TICH-2) trial
    Flaherty K, Bath PM, Dineen R, Law Z, Scutt P, Pocock S, et al.
    Trials, 2017 Dec 20;18(1):607.
    PMID: 29262841 DOI: 10.1186/s13063-017-2341-5
    RATIONALE: Aside from blood pressure lowering, treatment options for intracerebral haemorrhage remain limited and a proportion of patients will undergo early haematoma expansion with resultant significant morbidity and mortality. Tranexamic acid (TXA), an anti-fibrinolytic drug, has been shown to significantly reduce mortality in patients, who are bleeding following trauma, when given rapidly. TICH-2 is testing whether TXA is effective at improving outcome in spontaneous intracerebral haemorrhage (SICH).

    METHODS AND DESIGN: TICH-2 is a pragmatic, phase III, prospective, double-blind, randomised placebo-controlled trial. Two thousand adult (aged ≥ 18 years) patients with an acute SICH, within 8 h of stroke onset, will be randomised to receive TXA or the placebo control. The primary outcome is ordinal shift of modified Rankin Scale score at day 90. Analyses will be performed using intention-to-treat.

    RESULTS: This paper and its attached appendices describe the statistical analysis plan (SAP) for the trial and were developed and published prior to database lock and unblinding to treatment allocation. The SAP includes details of analyses to be undertaken and unpopulated tables which will be reported in the primary and key secondary publications. The database will be locked in early 2018, ready for publication of the results later in the same year.

    DISCUSSION: The SAP details the analyses that will be done to avoid bias arising from prior knowledge of the study findings. The trial will determine whether TXA can improve outcome after SICH, which currently has no definitive therapy.

    TRIAL REGISTRATION: ISRCTN registry, ID: ISRCTN93732214 . Registered on 17 January 2013.

    Matched MeSH terms: Data Interpretation, Statistical
  9. Fulltext Significant reduction of brain cysts caused by Toxoplasma gondii after treatment with spiramycin coadministered with metronidazole in a mouse model of chronic toxoplasmosis
    Chew WK, Segarra I, Ambu S, Mak JW
    Antimicrob Agents Chemother, 2012 Apr;56(4):1762-8.
    PMID: 22271863 DOI: 10.1128/AAC.05183-11
    Toxoplasma gondii is a parasite that generates latent cysts in the brain; reactivation of these cysts may lead to fatal toxoplasmic encephalitis, for which treatment remains unsuccessful. We assessed spiramycin pharmacokinetics coadministered with metronidazole, the eradication of brain cysts and the in vitro reactivation. Male BALB/c mice were fed 1,000 tachyzoites orally to develop chronic toxoplasmosis. Four weeks later, infected mice underwent different treatments: (i) infected untreated mice (n = 9), which received vehicle only; (ii) a spiramycin-only group (n = 9), 400 mg/kg daily for 7 days; (iii) a metronidazole-only group (n = 9), 500 mg/kg daily for 7 days; and (iv) a combination group (n = 9), which received both spiramycin (400 mg/kg) and metronidazole (500 mg/kg) daily for 7 days. An uninfected control group (n = 10) was administered vehicle only. After treatment, the brain cysts were counted, brain homogenates were cultured in confluent Vero cells, and cysts and tachyzoites were counted after 1 week. Separately, pharmacokinetic profiles (plasma and brain) were assessed after a single dose of spiramycin (400 mg/kg), metronidazole (500 mg/kg), or both. Metronidazole treatment increased the brain spiramycin area under the concentration-time curve from 0 h to ∞ (AUC(0-∞)) by 67% without affecting its plasma disposition. Metronidazole plasma and brain AUC(0-∞) values were reduced 9 and 62%, respectively, after spiramycin coadministration. Enhanced spiramycin brain exposure after coadministration reduced brain cysts 15-fold (79 ± 23 for the combination treatment versus 1,198 ± 153 for the untreated control group [P < 0.05]) and 10-fold versus the spiramycin-only group (768 ± 125). Metronidazole alone showed no effect (1,028 ± 149). Tachyzoites were absent in the brain. Spiramycin reduced in vitro reactivation. Metronidazole increased spiramycin brain penetration, causing a significant reduction of T. gondii brain cysts, with potential clinical translatability for chronic toxoplasmosis treatment.
    Matched MeSH terms: Data Interpretation, Statistical
  10. Reproducibility of different laser Doppler fluximetry parameters of postocclusive reactive hyperemia in human forearm skin
    Yvonne-Tee GB, Rasool AH, Halim AS, Rahman AR
    J Pharmacol Toxicol Methods, 2005 Sep-Oct;52(2):286-92.
    PMID: 16125628
    Postocclusive reactive hyperemia in forearm skin is a commonly used model for studying microvascular reactivity function, particularly in the assessment of vascular effect of topically applied pharmacological substances. In this study, we investigated the reproducibility of several different laser-Doppler-derived parameters in the measurement of postocclusive reactive hyperemia at forearm skin in healthy subjects.
    Matched MeSH terms: Data Interpretation, Statistical
  11. Rasch analysis of the Malaysian Secondary School Student Leadership Inventory (M3SLI)
    Ling MT
    J Appl Meas, 2016;17(3):365-392.
    PMID: 28027058
    The importance of instilling leadership skills in students has always been a main subject of discussion in Malaysia. Malaysian Secondary School Students Leadership Inventory (M3SLI) is an instrument which has been piloted tested in year 2013. The main purpose of this study is to examine and optimize the functioning of the rating scale categories in M3SLI by investigating the rating scale category counts, average and expected rating scale category measures, and steps calibrations. In detail, the study was aimed to (1) identify whether the five-point rating scale was functioning as intended and (2) review the effect of a rating scale category revision on the psychometric characteristics of M3SLI. The study was carried out on students aged between 13 to 18 years (2183 students) by stratified random sampling in 26 public schools in Sabah, Malaysia, with the results analysed using Winsteps. This study found that the rating scale of Personality and Values constructs needed to be modified while the scale for Leadership Skills was maintained. For future studies, other aspects of psychometric properties like differential item functioning (DIF) based on demographic variables such as gender, school locations and forms should be researched on prior to the use of the instrument.
    Matched MeSH terms: Data Interpretation, Statistical
  12. Random walker with improved weighting function for interactive medical image segmentation
    Yin LK, Rajeswari M
    Biomed Mater Eng, 2014;24(6):3333-41.
    PMID: 25227043 DOI: 10.3233/BME-141156
    To segment an image using the random walks algorithm; users are often required to initialize the approximate locations of the objects and background in the image. Due to its segmenting model that is mainly reflected by the relationship among the neighborhood pixels and its boundary conditions, random walks algorithm has made itself sensitive to the inputs of the seeds. Instead of considering the relationship between the neighborhood pixels solely, an attempt has been made to modify the weighting function that accounts for the intensity changes between the neighborhood nodes. Local affiliation within the defined neighborhood region of the two nodes is taken into consideration by incorporating an extra penalty term into the weighting function. Besides that, to better segment images, particularly medical images with texture features, GLCM variance is incorporated into the weighting function through kernel density estimation (KDE). The probability density of each pixel belonging to the initialized seeds is estimated and integrated into the weighting function. To test the performance of the proposed weighting model, several medical images that mainly made up of 174-brain tumor images are experimented. These experiments establish that the proposed method produces better segmentation results than the original random walks.
    Matched MeSH terms: Data Interpretation, Statistical*
  13. Random multispace quantization as an analytic mechanism for BioHashing of biometric and random identity inputs
    Teoh AB, Goh A, Ngo DC
    IEEE Trans Pattern Anal Mach Intell, 2006 Dec;28(12):1892-901.
    PMID: 17108365
    Biometric analysis for identity verification is becoming a widespread reality. Such implementations necessitate large-scale capture and storage of biometric data, which raises serious issues in terms of data privacy and (if such data is compromised) identity theft. These problems stem from the essential permanence of biometric data, which (unlike secret passwords or physical tokens) cannot be refreshed or reissued if compromised. Our previously presented biometric-hash framework prescribes the integration of external (password or token-derived) randomness with user-specific biometrics, resulting in bitstring outputs with security characteristics (i.e., noninvertibility) comparable to cryptographic ciphers or hashes. The resultant BioHashes are hence cancellable, i.e., straightforwardly revoked and reissued (via refreshed password or reissued token) if compromised. BioHashing furthermore enhances recognition effectiveness, which is explained in this paper as arising from the Random Multispace Quantization (RMQ) of biometric and external random inputs.
    Matched MeSH terms: Data Interpretation, Statistical
  14. Fulltext Quantified Uncertainties in Comparative Life Cycle Assessment: What Can Be Concluded?
    Mendoza Beltran A, Prado V, Font Vivanco D, Henriksson PJG, Guinée JB, Heijungs R
    Environ Sci Technol, 2018 02 20;52(4):2152-2161.
    PMID: 29406730 DOI: 10.1021/acs.est.7b06365
    Interpretation of comparative Life Cycle Assessment (LCA) results can be challenging in the presence of uncertainty. To aid in interpreting such results under the goal of any comparative LCA, we aim to provide guidance to practitioners by gaining insights into uncertainty-statistics methods (USMs). We review five USMs-discernibility analysis, impact category relevance, overlap area of probability distributions, null hypothesis significance testing (NHST), and modified NHST-and provide a common notation, terminology, and calculation platform. We further cross-compare all USMs by applying them to a case study on electric cars. USMs belong to a confirmatory or an exploratory statistics' branch, each serving different purposes to practitioners. Results highlight that common uncertainties and the magnitude of differences per impact are key in offering reliable insights. Common uncertainties are particularly important as disregarding them can lead to incorrect recommendations. On the basis of these considerations, we recommend the modified NHST as a confirmatory USM. We also recommend discernibility analysis as an exploratory USM along with recommendations for its improvement, as it disregards the magnitude of the differences. While further research is necessary to support our conclusions, the results and supporting material provided can help LCA practitioners in delivering a more robust basis for decision-making.
    Matched MeSH terms: Data Interpretation, Statistical*
  15. Fulltext Prevention of haematoma progression by tranexamic acid in intracerebral haemorrhage patients with and without spot sign on admission scan: a statistical analysis plan of a pre-specified sub-study of the TICH-2 trial
    Ovesen C, Jakobsen JC, Gluud C, Steiner T, Law Z, Flaherty K, et al.
    BMC Res Notes, 2018 Jun 13;11(1):379.
    PMID: 29895329 DOI: 10.1186/s13104-018-3481-8
    OBJECTIVE: We present the statistical analysis plan of a prespecified Tranexamic Acid for Hyperacute Primary Intracerebral Haemorrhage (TICH)-2 sub-study aiming to investigate, if tranexamic acid has a different effect in intracerebral haemorrhage patients with the spot sign on admission compared to spot sign negative patients. The TICH-2 trial recruited above 2000 participants with intracerebral haemorrhage arriving in hospital within 8 h after symptom onset. They were included irrespective of radiological signs of on-going haematoma expansion. Participants were randomised to tranexamic acid versus matching placebo. In this subgroup analysis, we will include all participants in TICH-2 with a computed tomography angiography on admission allowing adjudication of the participants' spot sign status.

    RESULTS: Primary outcome will be the ability of tranexamic acid to limit absolute haematoma volume on computed tomography at 24 h (± 12 h) after randomisation among spot sign positive and spot sign negative participants, respectively. Within all outcome measures, the effect of tranexamic acid in spot sign positive/negative participants will be compared using tests of interaction. This sub-study will investigate the important clinical hypothesis that spot sign positive patients might benefit more from administration of tranexamic acid compared to spot sign negative patients. Trial registration ISRCTN93732214 ( http://www.isrctn.com ).

    Matched MeSH terms: Data Interpretation, Statistical*
  16. Prevalence of Helicobacter pylori infection in endoscopy and non-endoscopy personnel: results of field survey with serology and 14C-urea breath test
    Goh KL, Parasakthi N, Ong KK
    Am J Gastroenterol, 1996 Feb;91(2):268-70.
    PMID: 8607491
    OBJECTIVES:
    The aims of the study were, first, to determine the prevalence of Helicobacter pylori (HP) among endoscopy personnel and a group of non-endoscopy volunteers and, second, to evaluate the usefulness of two noninvasive tests of diagnosis: serology and the urea breath test.

    METHODS:
    The two noninvasive methods of HP diagnosis, serology and 14C-urea breath test (UBT), were used in a cross-sectional survey of endoscopists, nurse-assistants, and non-endoscopy personnel.

    RESULTS:
    One hundred and thirty-five volunteers were recruited for the study. In 116, results of the two tests were in agreement (kappa = 0.645). Further analysis was based on the results of the UBT. Endoscopy personnel (endoscopists and nurse-assistants) as a group had a significantly higher incidence of HP than did controls (32.9% vs. 11.3%; p = 0.004). The two groups were comparable with regard to mean age, sex, ethnic distribution, and social class.

    CONCLUSIONS:
    HP infection is more prevalent among endoscopy personnel. Both diagnostic tests (serology and UBT) were convenient and relatively simple to perform, and results gave a high level of agreement.
    Matched MeSH terms: Data Interpretation, Statistical
  17. Fulltext Predicting physical time series using dynamic ridge polynomial neural networks
    Al-Jumeily D, Ghazali R, Hussain A
    PLoS One, 2014;9(8):e105766.
    PMID: 25157950 DOI: 10.1371/journal.pone.0105766
    Forecasting naturally occurring phenomena is a common problem in many domains of science, and this has been addressed and investigated by many scientists. The importance of time series prediction stems from the fact that it has wide range of applications, including control systems, engineering processes, environmental systems and economics. From the knowledge of some aspects of the previous behaviour of the system, the aim of the prediction process is to determine or predict its future behaviour. In this paper, we consider a novel application of a higher order polynomial neural network architecture called Dynamic Ridge Polynomial Neural Network that combines the properties of higher order and recurrent neural networks for the prediction of physical time series. In this study, four types of signals have been used, which are; The Lorenz attractor, mean value of the AE index, sunspot number, and heat wave temperature. The simulation results showed good improvements in terms of the signal to noise ratio in comparison to a number of higher order and feedforward neural networks in comparison to the benchmarked techniques.
    Matched MeSH terms: Data Interpretation, Statistical
  18. Fulltext Point Set Denoising Using Bootstrap-Based Radial Basis Function
    Liew KJ, Ramli A, Abd Majid A
    PLoS One, 2016;11(6):e0156724.
    PMID: 27315105 DOI: 10.1371/journal.pone.0156724
    This paper examines the application of a bootstrap test error estimation of radial basis functions, specifically thin-plate spline fitting, in surface smoothing. The presence of noisy data is a common issue of the point set model that is generated from 3D scanning devices, and hence, point set denoising is one of the main concerns in point set modelling. Bootstrap test error estimation, which is applied when searching for the smoothing parameters of radial basis functions, is revisited. The main contribution of this paper is a smoothing algorithm that relies on a bootstrap-based radial basis function. The proposed method incorporates a k-nearest neighbour search and then projects the point set to the approximated thin-plate spline surface. Therefore, the denoising process is achieved, and the features are well preserved. A comparison of the proposed method with other smoothing methods is also carried out in this study.
    Matched MeSH terms: Data Interpretation, Statistical*
  19. Fulltext New result of analytic functions related to Hurwitz zeta function
    Ghanim F, Darus M
    ScientificWorldJournal, 2013;2013:475643.
    PMID: 24396297 DOI: 10.1155/2013/475643
    By using a linear operator, we obtain some new results for a normalized analytic function f defined by means of the Hadamard product of Hurwitz zeta function. A class related to this function will be introduced and the properties will be discussed.
    Matched MeSH terms: Data Interpretation, Statistical
  20. Fulltext Neonatal clavicle fracture: a review of fourteen cases in east coast Peninsular Malaysia
    Awang, M.S., Abdul Razak, A.H., Che Ahmad, A., Mohd Rus, R.
    International Medical Journal Malaysia, 2017;16(2):79-83.
    MyJurnal
    Introduction: The purpose of this study is to identify the incidence of clavicle fractures in newborn
    associated with fetal, maternal and process of deliveries in Kuantan General Hospital from June 2012 until
    January 2014. This study is to determine epidemiological data of clavicle fractures, maternal and baby risk
    factors associated with clavicle fractures of newborn and its’ outcome.

    Methods: This is a prospective
    study. 13 patients were identified to fulfill the inclusion criteria of the study. The data of
    sociodemographic, associated fetal and maternal risk factors and the outcomes were recorded using
    proforma. The statistical data analysis was done using SPSS 12.0.

    Results: Out of 20,257 live births at our
    centre during the study period, 13 infants were diagnosed to have clavicle fractures, giving an incidence of
    0.64 per 1000 live births. There were 5 (38.5%) left, 7 (53.8%) right and one (7.7%) bilateral fracture. All
    fractures located at the mid shaft of the clavicle and none have associated brachial plexus injuries. All
    infants were delivered through vaginal delivery (61.5%); five through assisted delivery (instrumental); 2
    (15.4%) forcep and 3 (23.1%) vacuum. Two of the babies developed shoulder dystocia. The average birth
    weight was 3371 grams (SD 0.269) and mean gestational age was 38.7 weeks (SD 1.16). Five of the mothers
    (38.5%) were primigravida and eight (61.5%) were multigravida in which,7 (53.8%)were healthy without
    other co-morbidty, 5 (38.5%) having gestational diabetis and one (7.7%) hypertension. The average maternal
    weight was 62.0 kg and height 1.58 metres with average BMI of 24.16 (3.29SD). All eventually had a
    complete recovery at 6 weeks with clinical and radiological evident of fracture union.

    Conclusions: In
    conclusion, all patients with clavicle fractures were found following vaginal delivery. There were no
    associations between neonatal clavicle fractures with maternal or baby risk factors. All fractures healed
    without any complications.
    Matched MeSH terms: Data Interpretation, Statistical
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