Method Of Triads Research Articles

Validation of a food frequency questionnaire assessing dietary polyphenol exposure using the method of triads

When conducting research on polyphenols and their effects on health, it is of primary importance to use standardised and validated dietary assessment tools. This paper aims at assessing the validity of a food frequency questionnaire (FFQ) for quantifying dietary polyphenol exposure among healthy adults using the method of triads. Fifty-three healthy adults, aged 20–60, were included in the study. Total dietary polyphenol intake (TDP) estimated by the FFQ was compared with TDP measured by a 3-day food record (FR) and with urinary excretion levels of total polyphenols (TUP). Pearson correlations were calculated between methods. Validity coefficients (VC) were estimated between the three measurements and the ‘unknown’ true intake. There was a strong correlation between both dietary methods (r = 0.70, p < 0.0001). A moderate but significant association was observed between FFQ-derived TDP and TUP (r = 0.32, p = 0.020). The method of triads yielded a VC for the FFQ of 0.63 (95%CI: 0.41–0.84), indicating a strong relationship between FFQ-derived TDP and the true polyphenol intake. This study shows that the FFQ is an adequate tool not only for measuring dietary polyphenol exposure in nutrition epidemiological studies but also for guiding clinicians in dietary advice and counselling.

Polyunsaturated fatty acid food frequency questionnaire validation in people with end stage renal disease on dialysis.

To validate the polyunsaturated food frequency questionnaire (PUFA FFQ) and test for reproducibility in people with end stage renal disease on dialysis treatment. Participants (n = 32) completed the PUFA FFQ and three 24-hour recalls. Erythrocyte samples (n = 29) were used for erythrocyte fatty acid analysis. The triangular relationship between the PUFA FFQ, 24-hour recalls and the biomarker was assessed using the method of triads. Agreement between the two dietary methods was also assessed using Bland-Altman plots and classification by quintiles. Reproducibility was tested on a subset of the group (n = 8). The PUFA FFQ was a valid measure of all PUFA except for docosapentaenoic acid (DPA) and arachidonic acid (AA). Strong validity coefficients were found for n-3 long-chain PUFA (LCPUFA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) of 0.914 (95% CI: 0.665, 0.997) and 0.889 (95% CI: 0.706, 0.994), respectively. In the Bland-Altman plots 91-100% of observations fell between the limits of agreement for all PUFA. There were significant correlations between the initial FFQ and the repeat FFQ for all PUFA except DPA and AA. The PUFA FFQ is a valid tool for assessing PUFA intake in people with end stage renal disease.

Urinary sucrose and fructose to validate self-reported sugar intake in children and adolescents: results from the I.Family study.

Excessive consumption of free sugar increases the risk for non-communicable diseases where a proper assessment of this intake is necessary to correctly estimate its association with certain diseases. Urinary sugars have been suggested as objective biomarkers for total and free sugar intake in adults but less is known about this marker in children and adolescents. Therefore, the aim of this exploratory study is to evaluate the relative validity of self-reported intake using urinary sugars in children and adolescents. The study was conducted in a convenience subsample of 228 participants aged 5-18years of the I.Family study that investigates the determinants of food choices, lifestyle and health in European families. Total, free and intrinsic sugar intake (g/day) and sugar density (g/1000kcal) were assessed using 24-h dietary recalls (24HDRs). Urinary sucrose (USUC) and urinary fructose (UFRU) were measured in morning urine samples and corrected for creatinine excretion (USUC/Cr, UFRU/Cr). Correlation coefficients, the method of triads and linear regression models were used to investigate the relationship between intake of different types of sugar and urinary sugars. The correlation between usual sugar density calculated from multiple 24HDRs and the sum of USUC/Cr and UFRU/Cr (USUC/Cr + UFRU/Cr) was 0.38 (p < 0.001). The method of triads revealed validity coefficients for the 24HDR from 0.64 to 0.87. Linear regression models showed statistically significant positive associations between USUC/Cr + UFRU/Cr and the intake of total and free sugar. These findings support the relative validity of total and free sugar intake assessed by self-reported 24HDRs in children and adolescents.

The Influence of Triad Selection on the Preference Scaling Results

In the method of triads for a set of n objects all three element sets of objects are presented to the respondents. A respondent is asked to pick out the most similar and the least similar pair. The method of triads, despite its numerous advantages, is rarely used in practice. The number of triads is a cubic function of the number of objects and increases very rapidly with the number of objects. The aim of the study is to indicate the possibility of scaling preferences based on the reduced number of triads. It has also been examined whether the change of reduced set of triads influences the results of the scaling. The results of the analysis are illustrated by an empirical example in which pref­erence scaling for different sets of triads was performed with the use of TRISOSCAL program.

Systematic review of statistical approaches to quantify, or correct for, measurement error in a continuous exposure in nutritional epidemiology

BackgroundSeveral statistical approaches have been proposed to assess and correct for exposure measurement error. We aimed to provide a critical overview of the most common approaches used in nutritional epidemiology.MethodsMEDLINE, EMBASE, BIOSIS and CINAHL were searched for reports published in English up to May 2016 in order to ascertain studies that described methods aimed to quantify and/or correct for measurement error for a continuous exposure in nutritional epidemiology using a calibration study.ResultsWe identified 126 studies, 43 of which described statistical methods and 83 that applied any of these methods to a real dataset. The statistical approaches in the eligible studies were grouped into: a) approaches to quantify the relationship between different dietary assessment instruments and “true intake”, which were mostly based on correlation analysis and the method of triads; b) approaches to adjust point and interval estimates of diet-disease associations for measurement error, mostly based on regression calibration analysis and its extensions. Two approaches (multiple imputation and moment reconstruction) were identified that can deal with differential measurement error.ConclusionsFor regression calibration, the most common approach to correct for measurement error used in nutritional epidemiology, it is crucial to ensure that its assumptions and requirements are fully met. Analyses that investigate the impact of departures from the classical measurement error model on regression calibration estimates can be helpful to researchers in interpreting their findings. With regard to the possible use of alternative methods when regression calibration is not appropriate, the choice of method should depend on the measurement error model assumed, the availability of suitable calibration study data and the potential for bias due to violation of the classical measurement error model assumptions. On the basis of this review, we provide some practical advice for the use of methods to assess and adjust for measurement error in nutritional epidemiology.

Using the method of triads in the validation of a food frequency questionnaire to assess the consumption of fatty acids in adults.

It is of great value to develop valid instruments to estimate food consumption; for this purpose, the triads method has been applied in validation studies of dietary intake to evaluate the correlation between three measurements [food frequency questionnaire (FFQ), reference method and biomarker]. The main aim of the present study was to validate a FFQ for Brazilian adults by means of the method of triads by estimating the ingestion of total fatty acids based on the level of saturation. The present study enrolled 152 Brazilian adults of both sexes, who were residents in the city of Viçosa, Brazil. The ingestion of total saturated, monounsaturated, polyunsaturated, trans, linoleic and linolenic fatty acids was assessed by means of a FFQ, two food records, and biomarkers, which were detected by gas chromatography. The validation coefficients were calculated using the method of triads and concordance was determined by Kappa statistics. The FFQ was considered an adequate dietary method, because, based on the validation coefficients, it estimates the intake of total fat (0.84), as well as linolenic (0.90) and linoleic acids (0.31). A high concordance rate was confirmed for all nutrients assessed by the FFQ and food records. Regarding the biomarkers, linolenic acid and linoleic acid presented greater concordance. According to the validation coefficients, the FFQ precisely estimated total fat, linolenic acid and linoleic acid contents.

Validity of Self-Assessed Sexual Maturation Against Physician Assessments and Hormone Levels

To compare self-report and physician assessments of sexual maturation against serum hormone markers to evaluate the hypothesis that the validity of self-assessed sexual maturation is underestimated in traditional validation studies. We adapted a self-assessment instrument that 248 Mexican children and adolescents, aged 8-13 years, completed. The participants were examined by a trained pediatrician and provided fasting blood samples for measurement of reproductive hormones (eg, testosterone, estradiol, sex hormone-binding globulin, inhibin B) and other hormones (eg, C-peptide, insulin-like growth factor 1, leptin, dehydroepiandrosterone sulfate) known to change during adolescence. Spearman correlations (r) were calculated among the average rank of all hormones and self-assessed and physician-assessed Tanner stage. The method of triads was used to assess the validity of self-reports by estimating correlations between self-assessments and true but unobservable sexual maturation based on all available data. Bootstrap sampling was used to construct 95% CIs. The validity of self-reported genitalia staging for boys was modest (r = 0.50; 95% CI, 0.31-0.65) and inferior to physician assessment (r = 0.75; 95% CI, 0.56-0.93). Breast stage was well reported (r = 0.89; 95% CI, 0.79-0.97) and superior to physician assessment (r = 0.80; 95% CI, 0.70-0.89). Pubic hair stage reported by boys (r = 0.91; 95% CI, 0.79-0.99) and girls (r = 0.99; 95% CI, 0.96-1.00) was superior to physician assessment (r = 0.79; 95% CI, 0.57-0.97 and r = 0.91; 95% CI, 0.83-0.97, respectively). Self-assessment can be validly used in epidemiologic studies for evaluating sexual maturation in children; however, physician assessment may be necessary for accurate assessment of genitalia development in boys.

Validity of the Food Frequency Questionnaire Assessing the Folate Intake in Women of Reproductive Age Living in a Country without Food Fortification: Application of the Method of Triads.

The study aimed to examine the external validity of the Folate Food Frequency Questionnaire (F-FFQ) designed for assessing the folate intake in Serbian women of reproductive age. The F-FFQ was tested against repeated 24 h dietary recalls and correspondent nutritional biomarkers (red blood cells (RBC) and serum folate concentrations) using the method of triads. In a cross sectional study, 503 women aged 18–49 years completed dietary questionnaires and representative validation subsample (n = 50) provided fasting blood samples for biomarker analyses. Correlation coefficients were calculated between each of the dietary methods and three pair-wise correlations were applied for the calculation of validity coefficients. Correlation coefficients observed between F-FFQ and three 24 h recalls were r = 0.56 (p < 0.001) and r = 0.57 (p < 0.001) for total sample and validation group, respectively. Bland–Altman plot and cross-classification analyses indicated good agreement between methods. High validity coefficients were determined between the true intake (I) and dietary assessment methods, F-FFQ (Q) and 24 h dietary recalls (R) (ρQIrbc = 0.871 and ρQIser = 0.814; ρRIrbc = 0.652 and ρRIser = 0.698), and moderate ones for biomarkers (B) (ρBIrbc = 0.428 and ρBIser = 0.421). The F-FFQ is valid instrument for the assessment of dietary folate intake in women living in Serbia, a country without mandatory folic acid food fortification.

Use of the Method of Triads in the Validation of Sodium and Potassium Intake in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil).

IntroductionBiomarkers are a good choice to be used in the validation of food frequency questionnaire due to the independence of their random errors.ObjectiveTo assess the validity of the potassium and sodium intake estimated using the Food Frequency Questionnaire ELSA-Brasil.Subjects/MethodsA subsample of participants in the ELSA-Brasil cohort was included in this study in 2009. Sodium and potassium intake were estimated using three methods: Semi-quantitative food frequency questionnaire, 12-hour nocturnal urinary excretion and three 24-hour food records. Correlation coefficients were calculated between the methods, and the validity coefficient was calculated using the method of triads. The 95% confidence intervals for the validity coefficient were estimated using bootstrap sampling. Exact and adjacent agreement and disagreement of the estimated sodium and potassium intake quintiles were compared among three methods.ResultsThe sample consisted of 246 participants, aged 53±8 years, 52% of women. Validity coefficient for sodium were considered weak (рfood frequency questionnaire actual intake = 0.37 and рbiomarker actual intake = 0.21) and moderate (рfood records actual intake 0.56). The validity coefficient were higher for potassium (рfood frequency questionnaire actual intake = 0.60; рbiomarker actual intake = 0.42; рfood records actual intake = 0.79). Conclusions: The Food Frequency Questionnaire ELSA-Brasil showed good validity in estimating potassium intake in epidemiological studies. For sodium validity was weak, likely due to the non-quantification of the added salt to prepared food.

Validating Polyphenol Intake Estimates From a Food‐Frequency Questionnaire Using Repeated 24‐Hour Dietary Recalls and a Unique Method of Triads Approach With Two Biomarkers

Assessment of polyphenol intake in free-living subjects is challenging, mostly because of the difficulty in accurately measuring phenolic content and the wide presence of phenolic compounds in food...

Comparison of Multiple Measures of Noise Exposure in Paper Mills.

Noise exposures are associated with a host of adverse health effects, yet these exposures remain inadequately characterized in many industrial operations, including paper mills. We assessed noise at four paper mills using three measures: (i) personal noise dosimetry, (ii) area noise measurements, and (iii) questionnaire items addressing several different aspects of perceived noise exposure. We assessed exposures to noise characterized using the three measures and compared the relationships between them. We also estimated the validity of each of the three measures using a novel application of the Method of Triads, which does not appear to have been used previously in the occupational health literature. We collected 209 valid dosimetry measurements and collected perceived noise exposure survey items from 170 workers, along with 100 area measurements. We identified exposures in excess of 85 dBA at all mills. The dosimetry and area noise measurements assigned to individual subjects generally showed good agreement, but for some operations within mill, large differences between the two measures were observed, and a substantial fraction of paired measures differed by >5 dB. Perceived noise exposures varied greatly between the mills, particularly for an item related to difficulty speaking in noise. One perceived noise exposure item related to difficulty hearing due to noise showed strong and significant correlations with both dosimetry and area measurements. The Method of Triads analysis showed that dosimetry measures had the highest estimated validity coefficient (0.70), and that the best performing perceived exposure measure had validity that exceeded that of area measurements (0.48 versus 0.40, respectively). Workers in Swedish pulp mills have the potential for exposures to high levels of noise. Our results suggest that, while dosimetry remains the preferred approach to exposure assessment, perceived noise exposures can be used to evaluate potential exposures to noise in epidemiological studies.

Validation of a food frequency questionnaire to determine vitamin D intakes using the method of triads.

Dietary sources of vitamin D (both natural and fortified) are increasingly contributing to consumers' vitamin D intake and status. Therefore, the present study aimed to validate a vitamin D food frequency questionnaire (FFQ) for the assessment of habitual vitamin D intake. A total of 49 apparently healthy consenting adults (aged 18-64 years) from the local community were sampled at the end of winter. Dietary intakes were recorded using a 4-day weighed food record (4d-WFR) and a 17-item FFQ based on foods known to contribute to dietary vitamin D intake. Fasting vitamin D status was quantified by serum 25-hydroxyvitamin D [25(OH)D] using liquid chromatography tandem mass spectrometry. The method of triads was applied using these three measurements to determine the overall validity of the FFQ. Vitamin D intakes from 4d-WFR ranged between 0.42 and 31.65 μg day(-1), whereas intakes determined from the FFQ ranged from 1.03 to 36.08 μg day(-1). Serum 25(OH)D concentrations ranged between 12.89 and 279.00 nmol L(-1). The mean (SD) difference between the FFQ and 4d-WFR was +1.62 ( 3.86). There were strong correlations between the vitamin D intake estimated by the FFQ and that from the 4d-WFR (r = 0.562) and also with serum 25(OH)D concentrations (r = 0.567). Vitamin D intake estimated from the 4d-WFR was also strongly correlated with serum 25(OH)D concentrations (r = 0.411). The overall validity coefficient calculated using the method of triads was high (0.881). The vitamin D FFQ has been validated for use in future studies aiming to assess habitual vitamin D intake.

Validity of an FFQ assessing the vitamin D intake of young Serbian women living in a region without food fortification: the method of triads model.

The objective of the present study was to examine the external validity of an FFQ designed to estimate dietary vitamin D intake compared with a plasma biomarker and three repeated 24 h dietary recalls in women of reproductive age in Serbia, where there is no exposure to food fortified with vitamin D. The method of triads was applied. In a cross-sectional study, 422 women completed the Women and Reproductive Health FFQ (WRH-FFQ) during the winter months. From a representative subgroup (n 44), three 24 h dietary recalls and anthropometric parameters were collected as well as a fasting blood sample for vitamin D biomarker analyses. Correlation coefficients were calculated between each of the dietary methods. Validity coefficients, as a correlation between the measured and estimated 'true' exposure, were calculated using the method of triads. Bland-Altman plots were also constructed. Three major universities in Serbia. Healthy young women (n 422) aged 18-35 years. The WRH-FFQ estimate of vitamin D intake for all participants was 4.0 (sd 3.3) µg/d and 3.1 (sd 2.3) µg/d for the subgroup. Bland-Altman plots for these intakes showed high agreement. Validity coefficients for the FFQ, 24 h recall and biomarker were ρ QI=0.847 (95% CI 0.564, 0.928), ρ RI=0.810 (95% CI 0.537, 0.997) and ρ BI=0.499 (95% CI 0.190, 0.840), while the correlation coefficients were 0.686, 0.422 and 0.404. The FFQ applied in the present study is a valid tool for assessing dietary vitamin D intake in women living in Serbia, a region without mandatory vitamin D food fortification.

Validity and reliability of bioelectrical impedance analysis to estimate body fat percentage against air displacement plethysmography and dual‐energy X‐ray absorptiometry

AbstractAir displacement plethysmography (ADP) and dual‐energy X‐ray absorptiometry (DXA) are well‐regarded methods for predicting body fat percentage (BF%). Bioelectrical impedance analysis (BIA) also predicts BF% and has distinct advantages in research settings.AimTo assess the validity of BIA against ADP and DXA to measure BF%, and to test the reliability of each method.MethodsAdults (n = 166) with a wide range of body mass index (19–38 kg/m2) were tested twice during a 5‐day period. ADP was conducted in a BodPod (Life Measurement Inc, Concord, CA, USA); DXA measurements on a QDR Discovery A (Hologic) and BIA measurements used the InBody 230 (Biospace Ltd., Seoul, Korea). Agreement between measurements was analysed using t‐tests, effect size, linear regression models and method of triads (estimating true value).ResultsBIA showed excellent relative agreement to the estimated true value (ρ = 0.97 (0.96, 0.98)) and to ADP (R2 = 0.88) and DXA (R2 = 0.92), but wide limits of agreement (−4.25 to 8.37%). BIA underestimated BF% by 2%, across all values. DXA showed excellent relative agreement to the estimated true value (ρ = 0.97 (0.96, 0.98)) and with ADP (R2 = 0.92), good absolute agreement but wide limits of agreement (−6.13 to 6.91%) and under‐ and overestimation at high and low BF% levels, respectively. All methods showed excellent reliability with repeat measurements differing by less than 0.2% with very small 95% CIs.ConclusionsBIA may be a valid method in research and population samples. All three methods showed excellent reliability.

Non-Gaussian interaction information: estimation, optimization and diagnostic application of triadic wave resonance

Abstract. Non-Gaussian multivariate probability distributions, derived from climate and geofluid statistics, allow for nonlinear correlations between linearly uncorrelated components, due to joint Shannon negentropies. Triadic statistical dependence under pair-wise (total or partial) independence is thus possible. Synergy or interaction information among triads is estimated. We formulate an optimization method of triads in the space of orthogonal rotations of normalized principal components, relying on the maximization of third-order cross-cumulants. Its application to a minimal one-dimensional, periodic, advective model leads to enhanced triads that occur between oscillating components of circular or locally confined wave trains satisfying the triadic wave resonance condition.

Estimating and Testing Parameters of the Thurstonian Model for Torgerson's Method of Triads

Torgerson's complete method of triads is a famous and useful method for comparison of multiple samples. However, this method has not been used widely in the sensory field. One possible reason is that the Thurstonian model of the method is complicated and there is no published tables and available computer software for applications of the method. This paper discusses a Thurstonian model for a special case of the method with one control sample and two test samples. A table for Thurstonian discriminal distances and proportions of responses is produced. A set of R/S-Plus codes was developed and provided for applications of the method including estimations of parameters and covariance matrix, difference and similarity tests. A case study is provided for illustration of applications of the methods. The main novel contributions of this paper to the method are (1) using a computer-intensive approach to produce a simulation-based psychological function for the special case of the method and (2) using a delta method to derive a covariance matrix of the estimators of the two Thurstonian discriminal distances. Practical Applications In the situation of one control sample and two test samples, investigators are often interested in measuring perceptive distances between the control sample and test samples, and in testing if the samples are significantly different or similar. The Thurstonian model of Torgerson's method of triads can be used for the measurement. The table and R/S-Plus codes developed and provided in the paper can be used for the following objectives: (1) Estimating proportions of responses that one sample is more similar to a sample than to another sample; (2) Estimating and and the covariance matrix of the estimators for given proportions of responses; (3) Difference and similarity testing for the three samples; (4) Testing powers of the statistical tests and sample sizes; (5) Simulation experiments for the Thurstonian model of the special case of Torgerson's method and establishment of an empirical psychometric function for the model.

Validation of a food frequency questionnaire to assess habitual dietary vitamin D intake using the method of triads

Validation of a food frequency questionnaire to assess habitual dietary vitamin D intake using the method of triads

Метод триад при психологическом исследовании сложных объектов

The article deals with one of the variants of case study method – the method of triads for study of psychological consequences of the high intensity stressors influence on person. By comparing the three ca- ses – these patients with brain tumor diagnose, the specificity of the method is determined. It is shown that with method of cases comparison it is possible to distinguish the individual reactions to stress, determine the direction of the analysis of sample data, identify the trends of development of pathogenic mechanisms. Using the method of triads make it possible to identify the developmental mechanisms of such processes, with minimum loss of informative studies.

Optimal allocation of resources in a biomarker setting.

Nutrient intake is often measured with substantial error both in commonly used surrogate instruments such as a food frequency questionnaire (FFQ) and in gold standard-type instruments such as a diet record (DR). If there is a correlated error between the FFQ and DR, then standard measurement error correction methods based on regression calibration can produce biased estimates of the regression coefficient (λ) of true intake on surrogate intake. However, if a biomarker exists and the error in the biomarker is independent of the error in the FFQ and DR, then the method of triads can be used to obtain unbiased estimates of λ, provided that there are replicate biomarker data on at least a subsample of validation study subjects. Because biomarker measurements are expensive, for a fixed budget, one can use a either design where a large number of subjects have one biomarker measure and only a small subsample is replicated or a design that has a smaller number of subjects and has most or all subjects validated. The purpose of this paper is to optimize the proportion of subjects with replicated biomarker measures, where optimization is with respect to minimizing the variance of ln(λ̂). The methodology is illustrated using vitamin C intake data from the European Prospective Investigation into Cancer and Nutrition study where plasma vitamin C is the biomarker. In this example, the optimal validation study design is to have 21% of subjects with replicated biomarker measures.

PP190-SUN: Evaluation of Three Nutritional Screening Tools for Patients with Chronic Kidney Disease Under Dialysis by the Method of Triads

PP190-SUN: Evaluation of Three Nutritional Screening Tools for Patients with Chronic Kidney Disease Under Dialysis by the Method of Triads