Neural Networks for Portfolio Analysis in High-Frequency Trading.

High-frequency trading proposes new challenges to classical portfolio selection problems. Especially, the timely and accurate solution of portfolios is highly demanded in financial market nowadays. This article makes progress along this direction by proposing novel neural networks with softmax equalization to address the problem. To the best of our knowledge, this is the first time that softmax technique is used to deal with equation constraints in portfolio selections. Theoretical analysis shows that the proposed method is globally convergent to the optimum of the optimization formulation of portfolio selection. Experiments based on real stock data verify the effectiveness of the proposed solution. It is worth mentioning that the two proposed models achieve 5.50 % and 5.47 % less cost, respectively, than the solution obtained by using MATLAB dedicated solvers, which demonstrates the superiority of the proposed strategies.

New Dibenzocyclooctadiene Lignans and Phenolics from Kadsura heteroclite with Anti-Inflammatory Activity.

A chemical investigation of K. heteroclite led to isolation of two new dibenzocyclooctadienes (1 and 2) together with 14 known compounds (3-16) by using multiple chromatographic techniques. New compounds (1 and 2) were obtained and identified by spectroscopic methods (HR-ESI-MS, 1D and 2D NMR, and ECD) as well as by comparison of their experimental data with those reported in the literatures. All the isolates were evaluated for their ability to modulate TNF-α production in lipopolysaccharide (LPS) stimulated RAW264.7 cells. Among them, compound 5 displayed the most inhibition against tumor necrosis factor (TNF)-α production with IC50 value of 6.16±0.14 µM. Whereas, compounds (1, 3, and 6) showed the significant inhibition (IC50 values ranging from 9.41 to 14.54 µM), and compounds (2, 4, 9, 10, 13, 15, and 16) exhibited moderate inhibition (IC50 values ranging from 19.27 to 40.64 µM) toward TNF-α production, respectively.

Egret Swarm Optimization Algorithm: An Evolutionary Computation Approach for Model Free Optimization.

A novel meta-heuristic algorithm named Egret Swarm Optimization Algorithm (ESOA) is proposed in this paper, which is inspired by two egret species' hunting behavior (Great Egret and Snowy Egret). ESOA consists of three primary components: a sit-and-wait strategy, aggressive strategy as well as discriminant conditions. The learnable sit-and-wait strategy guides the egret to the most probable solution by applying a pseudo gradient estimator. The aggressive strategy uses random wandering and encirclement mechanisms to allow for optimal solution exploration. The discriminant model is utilized to balance the two strategies. The proposed approach provides a parallel framework and a strategy for parameter learning through historical information that can be adapted to most scenarios and has well stability. The performance of ESOA on 36 benchmark functions as well as 3 engineering problems are compared with Particle Swarm Optimization (PSO), Genetic Algorithm (GA), Differential Evolution (DE), Grey Wolf Optimizer (GWO), and Harris Hawks Optimization (HHO). The result proves the superior effectiveness and robustness of ESOA. ESOA acquires the winner in all unimodal functions and reaches statistic scores all above 9.9, while the scores are better in complex functions as 10.96 and 11.92.

Secondary metabolites from Valeriana jatamansi with their anti-inflammatory activity.

Valeriana jatamansi is hired as multiple remedies for treatment of insomnia, blood and circulatory disorders, asthma, dry cough, jaundice, seminal weakness, cardiac debility, and skin diseases in Vietnam. Our research discovered the phytochemical investigation of constituents from this herbal medicine resulted in the isolation of two new compounds (jatamansides A (4) and B (7)) together with 16 known ones from the whole plant. Their structures were established by using spectroscopic techniques (multinuclear and multidimensional nuclear magnetic resonance, infrared, ultraviolet-visible), mass spectrometry, hydrolysis analysis, or comparing their NMR data to those reported in the literature. In addition, all the isolates were evaluated for their inhibitory effect against TNF-α production in LPS-stimulated on RAW264.7 cells with significant inhibition.

Normal values for high-resolution anorectal manometry in healthy young adults: evidence from Vietnam.

BACKGROUND: High-resolution anorectal manometry (HRAM) has been developed to improve measurement of anorectal functions. This study aims to identify normal HRAM values in healthy young Vietnamese adults. METHODS: We conducted a cross-sectional study at the National Hospital of Traditional Medicine (Hanoi, Vietnam) from July through December 2014. Healthy young adults were invited to participate in the study. All anorectal measurement values were performed using the ISOLAB high-resolution manometry system. Differences between groups were analyzed using Student's t-tests. RESULTS: Thirty healthy young adults, including 15 males and 15 females aged 19-26 years, were recruited. Mean functional anal canal length was 3.4 ± 0.5 cm (range: 2.4-4.8 mm). Mean maximum resting pressure, mean maximum squeezing pressure, mean maximum coughing pressure, and mean maximum strain pressure were 65.5, 168.0, 125.9, and 84.2 mm Hg, respectively. All anal pressure values were significantly different between males and females. For rectal sensation measurements, only the volume at first sensation was significantly higher in males than in females. CONCLUSIONS: This study provides normal HRAM value for healthy young adults in Vietnam. Sex may influence anal pressure and first rectal sensation values in this cohort. Further studies should be conducted in order to improve the quality of HRAM normal values and to confirm the effects of sex.

Pseudomonas neustonica sp. nov., isolated from the sea surface microlayer of the Ross Sea (Antarctica).

Gram-stain-negative, aerobic and rod-shaped bacterial strains, designated SSM26T and SSM44, were isolated from a sea surface microlayer sample from the Ross Sea, Antarctica. Analysis of the 16S rRNA gene sequences of strains SSM26T and SSM44 revealed a clear affiliation with the genus Pseudomonas. Based on the results of phylogenetic analysis, strains SSM26T and SSM44 showed the closest phylogenetic relationship with the species Pseudomonas sabulinigri KCTC 22137T with the 16S rRNA gene sequence similarity level of 98.5 %. Strains SSM26T and SSM44 grew optimally at 30 °C, pH 7.0-7.5 and 0.5-10.0 % NaCl (w/v). The major cellular fatty acids were C18 : 1 ω7c (31.3-34.9 %), C16 : 0 (15.5-20.2 %), summed feature 3 (C16 : 1 ω7c/C16 : 1 ω6c; 19.5-25.4 %) and C12 : 0 (6.0-9.3 %). The genomic DNA G+C content of each strain was 56.2 mol%. Genomic relatedness analyses based on the average nucleotide identity and the genome-to-genome distance showed that strains SSM26T and SSM44 constituted a single species that was clearly distinguishable from its phylogenetically close relatives. The combined phenotypic, chemotaxonomic, genomic and phylogenetic data also showed that strains SSM26T and SSM44 could be distinguished from validly published members of the genus Pseudomonas. Thus, these strains should be classified as representing a novel species in the genus Pseudomonas, for which the name Pseudomonas neustonica sp. nov. is proposed with the type strain SSM26T (=KCCM 43193T=JCM 31284T=PAMC 28426T) and a sister strain SSM44 (=KCCM 43194=JCM 31285=PAMC 28427).

Anorectal Functional Outcomes Following Doppler-Guided Transanal Hemorrhoidal Dearterialization: Evidence from Vietnam.

INTRODUCTION: Doppler-guided transanal hemorrhoidal dearterialization (THD) was considered a less invasive and innovative method to treat hemorrhoidal disease, but it may impact the anal area during dearterialization and mucopexy. Thus, this study aimed to assess any changes in anorectal manometry of grade III and IV hemorrhoidal patients following THD treatment. METHODS: This prospective observational study was conducted with patients who had grades III and IV hemorrhoidal disease. The patients were treated using THD at the Department of Surgery in the National Hospital of Traditional Medicine (Hanoi, Vietnam) between June 2012 and December 2013. Anorectal manometry was performed prior to THD and again between 6 and 12 months following the procedure. RESULTS: A total of 40 patients were enrolled in the study, including 32 with grade III hemorrhoids and 8 with grade IV hemorrhoids. The proportion of male patients (65%) was higher than that of female patients (35%), and the majority of patients (82.5%) were > 40 years old. The mean duration of symptoms prior to treatment was 12.3 years. The mean length of the anal sphincter was unchanged before and after THD (3.64 ± 0.40 cm prior to treatment vs. 3.66 ± 0.48 cm following treatment; p = 0.57). Significant differences in treatment-related changes were detected for all anorectal manometric measurements except maximum squeezing pressure (p < 0.05). No patient showed anal stenosis or fecal incontinence. CONCLUSION: The THD technique did not change the length of the anal sphincter 6 months after hemorrhoid treatment. The values of anal pressure and rectal sensation decreased almost significantly between treatment and the follow-up visit. We suggest that further studies, which include larger sample sizes, should be conducted to confirm THD effectiveness in terms of anorectal functions.

Comparison of Doppler-Guided Transanal Hemorrhoidal Dearterialization for Grade III and IV Hemorrhoids in Vietnam.

INTRODUCTION: This study aimed to assess the short- and long-term outcomes of Doppler-guided transanal hemorrhoidal dearterialization (THD) for grade III and IV hemorrhoidal disease in Vietnam. METHODS: In a prospective observational design, patients treated for grade III and IV hemorrhoidal disease with the THD method at the National Hospital of Traditional Medicine (Hanoi, Vietnam) were included between June 2012 and December 2013. Patients were evaluated postoperatively at the time they were discharged from the hospital (short-term outcome) and 6 months after surgery (long-term outcome). RESULTS: A total of 128 patients were enrolled in the study, 94 were classified with grade III disease and 34 with grade IV. Grade IV hemorrhoidal patients reported on average 18.2 years of disease symptom duration, while grade III hemorrhoidal patients reported 11.2 years. All patients with grade III and grade IV hemorrhoidal disease had good outcomes at discharge day and reported to return to work in a median of 6 days after THD. At long-term follow-up, the results were good for 80.9% of patients from grade III hemorrhoidal disease and 61.8% of patients from grade IV hemorrhoidal disease. Patient satisfaction with the procedure and outcomes was 93.6% for grade III and 85.3% for grade IV hemorrhoidal patients. CONCLUSIONS: The THD technique was shown to be safe for both grade III and IV hemorrhoidal patients. The THD technique showed better results with grade III hemorrhoidal patients as compared to grade IV hemorrhoidal patients.

Caretaker mental health and family environment factors are associated with adolescent psychiatric problems in a Vietnamese sample.

Little is known about risk factors for adolescent mental health in Vietnam. The present study investigated the relationship between caretaker mental health and adolescent mental health in a cross-sectional Vietnamese sample. Primary caretakers completed measures of their own mental distress and general health status using the Self-Reporting Questionnaire-20 (SRQ-20) as well as reports of adolescent mental health using the parent version of the Strengths and Difficulties Questionnaire (SDQ). Multivariate regression models were used to examine the relationships between the caretaker and adolescent health variables. The demographic factors of age, sex, ethnicity, religious affiliation, and household wealth status demonstrated significant relationships with SDQ subscale scores. Caretaker mental health was positively associated with adolescent mental health, and this association remained significant even after accounting for other relevant demographic variables and caretaker general health status. Understanding correlates of adolescent mental health difficulties may help identify youth and families at risk for developing psychiatric problems and inform mental health interventions in Vietnam.

Using the SRQ-20 factor structure to examine changes in mental distress following typhoon exposure.

Empirical research is limited regarding postdisaster assessment of distress in developing nations. This study aimed to evaluate the factor structure of the 20-item Self-Reporting Questionnaire (SRQ-20) before and after an acute trauma, Typhoon Xangsane, in order to examine changes in mental health symptoms in an epidemiologic sample of Vietnamese adults. The study examined a model estimating individual item factor loadings, thresholds, and a latent change factor for the SRQ-20's single "general distress" common factor. The covariates of sex, age, and severity of typhoon exposure were used to evaluate the disaster-induced changes in SRQ-20 scores while accounting for possible differences in the relationship between individual measurement scale items and the latent mental health construct. Evidence for measurement noninvariance was found. However, allowing sex and age effects on the pre-typhoon and post-typhoon factors accounted for much of the noninvariance in the SRQ-20 measurement structure. A test of no latent change failed, indicating that the SRQ-20 detected significant individual differences in distress between pre- and post-typhoon assessment. Conditioning on age and sex, several typhoon exposure variables differentially predicted levels of distress change, including evacuation, personal injury, and peri-event fear. On average, females and older individuals reported higher levels of distress than males and younger individuals, respectively. The SRQ-20 is a valid and reasonably stable instrument that may be used in postdisaster contexts to assess emotional distress and individual changes in mental health symptoms.

Characteristics of individuals meeting criteria for new onset panic attacks following exposure to a typhoon.

The association between trauma exposure and panic attacks has received increased attention over the past decade, with mounting evidence suggesting an overlapping etiologic pathway. This study examined the incidence of new onset panic attacks in 775 Vietnamese individuals in the 2-3 months following Typhoon Xangsane. Pre-typhoon (Wave 1) and post-typhoon (Wave 2) assessments were conducted, allowing for consideration of factors occurring prior to the typhoon in addition to typhoon-relevant responding. Of the 775 participants, 11.6% (n=90) met criteria for lifetime panic attack pre-typhoon and 2.8% (n=22) met post-typhoon panic attack criteria. Individuals with pre-typhoon panic were significantly older and reported less education compared to the no-panic group. Individuals in both panic groups were more likely to screen positive on a Wave1 psychiatric screening measure, endorse greater typhoon exposure and prior traumatic event exposure and were significantly more likely to meet DSM-IV criteria for posttraumatic stress disorder (PTSD) and major depression (MDD) post-typhoon compared with persons reporting no history of panic attacks. Pre and post-typhoon panic exhibited similar patterns across variables and both panic conditions were associated with the development of PTSD and MDD, suggesting that persons experiencing panic attacks may represent a vulnerable population in need of early intervention services.

Pre-typhoon socioeconomic status factors predict post-typhoon psychiatric symptoms in a Vietnamese sample.

PURPOSE: Exposure to natural disasters has been associated with increased risk for various forms of psychopathology. Evidence indicates that socioeconomic status (SES) may be important for understanding post-disaster psychiatric distress; however, studies of SES-relevant factors in non-Western, disaster-exposed samples are lacking. The primary aim of the current study was to examine the role of pre-typhoon SES-relevant factors in relation to post-typhoon psychiatric symptoms among Vietnamese individuals exposed to Typhoon Xangsane. METHODS: In 2006, Typhoon Xangsane disrupted a mental health needs assessment in Vietnam in which the Self Reporting Questionnaire-20 (SRQ-20), and the Demographic and Health Surveys Wealth Index, a measure of SES created for use in low-income countries, were administered pre-typhoon. The SRQ-20 was re-administered post-typhoon. RESULTS: Results of a linear mixed model indicated that the covariates of older age, female sex, and higher levels of pre-typhoon psychiatric symptoms were associated with higher levels of post-typhoon psychiatric symptoms. Analysis of SES indicators revealed that owning fewer consumer goods, having lower quality of household services, and having attained less education were associated with higher levels of post-typhoon symptoms, above and beyond the covariates, whereas quality of the household build, employment status, and insurance status were not related to post-typhoon psychiatric symptoms. CONCLUSION: Even after controlling for demographic characteristics and pre-typhoon psychiatric symptoms, certain SES factors uniquely predicted post-typhoon psychiatric distress. These SES characteristics may be useful for identifying individuals in developing countries who are in need of early intervention following disaster exposure.

Pretyphoon panic attack history moderates the relationship between degree of typhoon exposure and posttyphoon PTSD and depression in a Vietnamese sample.

BACKGROUND: Predisaster risk factors are related to postdisaster psychopathology even at relatively low levels of disaster exposure. A history of panic attacks (PA) may convey risk for postdisaster psychopathology and has been linked to a wide range of psychiatric disorders in Western and non-Western samples. The present study examined the main and interactive effects of pretyphoon PA and level of typhoon exposure in the onset of posttyphoon posttraumatic stress disorder (PTSD), major depression (MDD), and generalized anxiety disorder (GAD) in a Vietnamese sample of typhoon survivors. METHODS: Typhoon Xangsane interrupted a Vietnamese epidemiological mental health needs assessment, providing a rare opportunity for preand posttyphoon assessments. Hierarchical logistic regression analyses evaluated whether the main and interactive effects of typhoon exposure severity and PA history were significantly related to posttyphoon diagnoses, above and beyond age, health status, pretyphoon psychiatric screening results, and history of potentially traumatic events. RESULTS: PA history moderated the relationship between severity of typhoon exposure and posttyphoon PTSD and MDD, but not GAD. Specifically, greater degree of exposure to the typhoon was significantly related to increased likelihood of postdisaster PTSD and MDD among individuals without a history of PA, above and beyond variance accounted for by pretyphoon psychiatric screening results. Individuals with a history of PA evidenced greater risk for postdisaster PTSD and MDD regardless of severity of typhoon exposure. CONCLUSIONS: Preexisting PA may affect the nature of the relationship between disaster characteristics and prevalence of postdisaster PTSD and MDD within Vietnamese samples.

Evaluation of the psychometric properties of the Self-Reporting Questionnaire (SRQ-20) in a sample of Vietnamese adults.

PURPOSE: There are significant gaps in the literature on the prevalence of mental health problems and associated needs in Vietnam. A thorough understanding of culture-specific expressions of psychiatric distress is vital for the identification of the mental health needs of a community, and more research on the development and evaluation of culturally-sensitive mental health assessments is warranted. This study aims to evaluate the psychometric properties of the World Health Organization 20-item Self-Reporting Questionnaire (SRQ-20) in an epidemiologic study of Vietnamese adults. METHODS: A latent variable modeling approach investigated the underlying factor structure of the SRQ-20 items. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were conducted on SRQ-20 item-level data gathered from 4980 participants. RESULTS: Based on scree plots and EFA results, two latent structures were deemed plausible and were subsequently subjected to further modeling. A bi-factor model (BFM) and a correlated three-factor model solution (Negative Affect, Somatic Complaints, and Hopelessness) provided reasonable fits. The BFM specifies a single dominant General Distress factor (all SRQ-20 items) with orthogonal group factors for the subsets of items: Negative Affect (9 items), Somatic Complaints (8 items), and Hopelessness (3 items). This model fit the data as well or better than the three-factor model. Results also showed differences in endorsement rates of SRQ-20 items among males and females. CONCLUSIONS: Study results provide an evaluation of the psychometric properties of a commonly used screening tool and offer insight into the presentation of mental distress in a representative sample of Vietnamese adults.

Greater length-for-age increases the odds of attaining motor milestones in Vietnamese children aged 5-18 months.

Early childhood malnutrition has been associated with delayed development. Limited data exist however about the timing of developmental delay early in life. We assessed motor milestone (MM) achievement using the World Health Organization's windows of achievement for gross motor milestones. We performed secondary analysis of baseline data of 158 Vietnamese children aged 5-18 months from a randomized community intervention trial. Median age of motor milestone achievement was compared to WHO reported medians. Multivariate logistic regression was used to identify socioeconomic, anthropometric and dietary factors associated with motor milestone achievement during the windows of achievement. Thirty four per cent of the children were stunted. Median age of MM achievement of Vietnamese children lagged by 2.4-3.7 months, compared to the WHO median for all MMs. Greater length-for-age increased the odds for walking with assistance, standing alone and walking alone by more than 3 times. Greater weight-for-age increased the odds by 3.6 for hand-and-knees crawling. Likewise, frequency of daily complementary feeding raised the odds by 3.6 for standing with assistance. In this first application of WHO windows of achievement in Viet Nam, pre-schoolers achieved motor milestones later than WHO reported median age. High prevalence of stunting and association of length-for-age with motor milestone achievement underscore the importance of addressing chronic malnutrition to optimize children's growth and development.

Cytotoxic and anti-inflammatory cembranoids from the Vietnamese soft coral Lobophytum laevigatum.

Four new cembranoids, namely laevigatol A-D (1-4), and six known metabolites (5-10), were isolated from the Vietnamese soft coral Lobophytum laevigatum. The structures of these compounds were elucidated by extensive spectroscopic analyses, and the absolute stereochemistry of 1 was determined using the modified Mosher's method. Compounds 5, and 7-10 exhibited cytotoxic activity against selected human cancer cell lines. Compounds 1, 2, 8, and 9 showed dose-dependent inhibitory effects on the TNFα-induced NF-κB transcriptional activity in Hep-G2 cells. Moreover, compounds 1, 2, 8, and 9 significantly inhibited the induction of COX-2 and iNOS mRNA dose-dependently, indicating that these compounds attenuated the synthesis of these transcripts at the transcriptional level.

Cytotoxic and PPARs transcriptional activities of sterols from the Vietnamese soft coral Lobophytum laevigatum.

A new unusual sterol, named lobophytosterol (1), and five known metabolites (2-6) were isolated from the methanol extract of the soft coral Lobophytum laevigatum. Their chemical structures were elucidated by extensive spectroscopic analysis and comparison with those reported in the literature. The absolute stereochemistry of 1 was determined using a modified Mosher's method. Compounds 1-3 showed cytotoxic activity against HCT-116 cells with IC(50) values of 3.2, 6.9 and 18.1 µM, respectively. Compound 1 additionally displayed cytotoxic effects on A549 and HL-60 cells with IC(50) values of 4.5 and 5.6 µM, respectively. Treatment of these cells with compound 1 resulted in an induction of apoptosis evident by chromatin condensation in treated cells. Besides, compounds 2, 4, and 6 significantly upregulated PPARs transcriptional activity dose-dependently in Hep-G2 cells. Taken together, these data suggest that compound 1 might inhibit the growth of the cancer cells by the induction of apoptosis, and compounds 2, 4, and 6 might act as specific agonists for PPARα, PPARδ, and PPARγ and may therefore regulate cellular glucose, lipid, and cholesterol metabolism.

Prevalence and correlates of probable adolescent mental health problems reported by parents in Vietnam.

PURPOSE: The purpose of the present study was to estimate the prevalence of probable mental health problems in an epidemiologic study of Vietnamese adolescents. A secondary aim was to examine the correlates of probable mental health caseness. METHODS: Interviewers visited 1,914 households that were randomly selected to participate in a multi-agency study of mental health in select provinces of Vietnam. Semi-structured interviews assessed adolescent mental health problems using the Strengths and Difficulties Questionnaire (SDQ) parent informant version, and additionally the interviewers collected information on demographic variables (age, gender, ethnic group, religious affiliation, social capital). The final sample included data on 1,368 adolescents (aged 11-18 years). RESULTS: The average score on the total problem composite of the SDQ scale was 6.66 (SD=4.89), and 9.1% of the sample was considered a case (n=124). Bivariate analyses were conducted to determine which demographic variables were related to the SDQ case/non-case score. All variables except gender were significant in bivariate analyses, and therefore were entered into a logistic regression. Results indicated that age, religion, and wealth remained significant predictors of probable caseness. CONCLUSIONS: Overall, prevalence estimates of mental health problems generated by the SDQ were consistent with those reported in the US and other Western and non-Western samples. Results of the current study suggest some concordance of risk and protective factors between Western and Vietnamese youth (i.e., age and SES).

Estimating mental distress in Vietnam: the use of the SRQ-20.

BACKGROUND: Community-based estimates of psychopathology prevalence in developing countries such as Vietnam, are needed to reduce presumed significant burden of poor mental health. AIMS: This study derived population-based prevalence estimates of mental distress, as measured by the SRQ-20, in a community sample of 4,981 adults living in Vietnam. This study also examined correlates of mental distress based on SRQ-20 caseness indications. Risk and protective factors were identified in terms of their unique contribution to caseness. RESULTS: Using a cut-off of 7/8, 19.2% of the sample was considered to be a probable case (n = 954), with females endorsing more items than males. Marital status and employment status were not associated with mental health distress. Higher wealth, endorsing religious affiliation, and self-reports of good health were associated with lower SRQ-20 scores. Age and being female were associated with higher SRQ-20 scores. CONCLUSIONS: A single item was as adequate a measure of wealth as multi-item rating scales. Our estimate of mental distress using the SRQ-20 is much greater than that of other studies, and in contrast to western prevalence studies, age was not a protective factor in this study. The SRQ-20 is a brief, cost-effective and reasonably valid measure of both community and individual mental distress.

Does Interviewer Status Matter? An examination of Lay Interviewers and Medical Doctor Interviewers in an Epidemiological Study in Vietnam.

In 2006, typhoon Xangsane disrupted a large-scale multi-agency mental health study of 4,982 individuals in the DaNang province of Vietnam. Following this disaster, 795 of the original 4,982 participants were randomly assigned to be re-interviewed by either a medical doctor or a lay interviewer using structured clinical interviews to determine prevalence of lifetime and post-typhoon post-traumatic stress disorder (PTSD), major depressive disorder (MDD), panic disorder (PD), and generalized anxiety disorder (GAD) according to the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (APA, 1994). The aim of the present study was to determine if prevalence of disorders differed by interviewer type. Bivariate analyses and multivariable analyses, as well as internal reliability estimates, all indicated no significant differences between the medical doctor interviewers versus the lay interviewers. This held for both lifetime prevalence as well as post-typhoon prevalence of disorders. This study has implications for epidemiologic studies, as it indicates that with adequate training, the use of lay interviewers may be a valid means of data collection.