Paired Comparison Experiments Research Articles

Reading comfort in relation to monitor and ambient luminance levels: A study using continuous rating scale and paired comparison methodology

In this work, it is investigated how reading comfort is influenced by monitor and ambient luminance levels, when employing high-luminance monitors. High-luminance monitors can be used to get more light on the eye and elicit non-image-forming effects. However, this might lead to reduced reading comfort. Two psychophysical methods, a continuous rating scale and paired comparison, were employed to investigate reading comfort in relation to the luminance of the monitor and the ambient environment. The results of 18 observers for the continuous rating scale experiment (aged 20 y to 30 y) and 20 observers for the paired comparison experiment (aged 20 y to 37 y) indicate that reading comfort is significantly influenced by both monitor and ambient luminance levels The paired comparison methodology provided more distinctive capabilities and thus offered a deeper insight. In contrast to prior work suggesting a linear relation between monitor luminance and preferred ambient luminance, the current results indicate that the reading comfort level reaches a tipping or saturation point. A monitor luminance level of 260 cd m−2 combined with an ambient luminance level of 68 cd m−2 provided the highest reading comfort. This reading comfort could not be matched when employing a higher monitor luminance level of 700 cd m−2.

Discordances in patients' and physicians' perspectives on which contextual factors should be accounted for during smoking cessation.

Smoking cessation interventions requires attending to the circumstances and needs of individual patients. We aimed at highlighting the discordances between patients' and physicians' perspectives on contextual factors that should be considered during smoking cessation. We identified 36 contextual factors identified that should be considered during smoking cessation using PubMed and interviewing general practitioners. Physicians recruited through social networks campaigns and smoker or former smoker patients from the ComPaRe cohort selected the factors they considered most relevant in two online paired comparison experiment. Bradley Terry Luce models estimated the ability of each factor (i.e. the probability to be preferred). We calculated the Pearson's correlation and the intraclass correlation coefficients for the contextual factor from each perspective and compared the ranking of the 10 contextual factors with the highest abilities. Seven hundred and ninety-three patients' and 795 physicians' perspectives estimated the ability (i.e., importance) of the contextual factors in 11 963 paired comparisons. We found a high correlation between physicians' and patients' perspectives of the contextual factors to be considered for smoking cessation (r = 0.76, P < 0.0001). However, the agreement between the abilities of contextual factors was poor (ICC = 0.42 [-0.10; 0.75]; P = 0.09). Fine-grain analysis of participants' answers revealed many discrepancies. For example, 40% factors ranked in the top 10 most important for physicians were not in patients' top 10 ranking. Our results highlight the importance of patient-centered care, the need to engage discussions about patients' values, beyond what is thought to be important, to avoid overlooking their real context.

A methodological framework allows the identification of personomic markers to consider when designing personalized interventions

ObjectivesTo develop a methodological framework to identify and prioritize personomic markers (e.g., psychosocial situation, beliefs…) to consider for personalizing interventions and to test in smoking cessation interventions. Study Design and Setting(1) We identified potential personomic markers considered in protocols of personalized interventions, in reviews of predictors of smoking cessation, and in interviews with general practitioners. (2) Physicians, and patient smokers or former smokers selected the markers they considered most relevant during online paired comparison experiments. Data were analyzed with Bradley Terry Luce models. ResultsThirty-six personomic markers were identified from research evidence. They were evaluated by 795 physicians (median age: 34, IQR [30–38]; 95% general practitioners) and 793 patients (median age: 54, IQR [42–64], 71.4% former smokers) during 11,963 paired comparisons. Physicians identified patients' motivation for quitting (e.g., Prochaska stages), patients' preferences, and patients’ fears and beliefs (e.g., concerns about weight gain) as the most relevant elements to personalize smoking cessation. Patients considered their motivation for quitting, smoking behavior (e.g., smoking at home/at work), and tobacco dependence (e.g., Fagerström Test) as the most relevant elements to consider. ConclusionWe provide a methodological framework to prioritize which personomic markers should be considered when developing smoking cessation interventions.

On the design of paired comparison experiments with application

In practice, paired comparison experiments involving pairs of either full or partial profiles are frequently used. When all attributes have a general common number of levels, the problem of finding optimal designs is considered in the presence of a second-order interaction model. In this setting, the D-optimal designs for the second-order interaction model have both types of pairs in which either all attributes have different levels or approximately half of the attributes are different. The proposed optimal designs can be used as a benchmark to compare any design for estimating main effects and two- and three-attribute interactions. A practical situation that incorporates the corresponding second-order interactions is covered.

Perceived Color Gamut in Images: From Boundary to Difference.

A larger display color gamut volume (CGV) is expected to produce higher perceived brightness and colorfulness of the images displayed. However, display control algorithms such as gamut mapping and color conversion need to be carefully controlled to fully take advantage of the higher luminance and more saturated display primaries. Using RGBW displays (RGB plus a white channel) as a special case in contrast to RGB displays, it is demonstrated that a larger RGB display gamut enclosed by the boundary did not guarantee a larger color gamut perceived in images. Five gamuts with different white channel contributions were simulated, and seven different image contents were curated and rendered on each display. Using a paired comparison experiment with 33 observers, the perceived scales of color gamut as perceived brightness and colorfulness were derived. The results show more correlation with the image-wise than display-wise CGV and can be explained with image color differences. Our findings highlight the importance of considering image contents when optimizing display gamut volume, which can be guided by such image-wise analysis.

Multi-Channel LED Luminaires: An Object-Oriented Approach for Retail Lighting Based on the SOR Framework

In this paper, a method to find the optimum spectrum for the illumination of objects in a retail environment is presented. A variety of familiar objects are illuminated with a number of illuminants of a predefined Correlated Color Temperature (CCT) of 3000 K, strategically selected from the entire range of metamers, which can be generated by the multi-channel luminaire under test. The solution space has been derived by solving basic colorimetric equations using a brute force method. In a paired comparison experiment, observers had to select the most “attractive” appearance for the presented objects. The results illustrate that objects may indeed appear more attractive for a statistically meaningful number of observers under a particular lighting condition. Assuming attractiveness of an object as a stimulus in the SOR framework, this approach facilitates the generation and the selection of the “optimum” spectrum based on the goals of the stakeholders in retail lighting applications.

Approximate and Exact Optimal Designs for Paired Comparison Experiments

In this article, the problem of finding optimal paired comparison approximate and exact designs for the identification of main effects and two and three and four attribute interactions, when the alternatives are characterized by either full profiles or partial profiles, is considered. The resulting designs are also optimal under the indifference assumption of equal choice probabilities for a multinomial logit model when the choice sets are pairs. AMS subject classification: 62K05, 62J15, 62K15

Investigating the tactile warmth of untreated and modified wood surfaces by measuring cold sensitivity in paired-comparison experiments

ABSTRACT The tactile warmth quality of various untreated and modified wood surfaces was compared at a room temperature of 22°C using the Thurstone’s psychophysical method of paired comparison. The test surfaces included 12 varieties of untreated and modified wooden surfaces. A total of 17 participants took part in the experiments, in which they compared 33 specimen pairs arising from various surface combinations. The results demonstrated the considerable differences in tactile warmth quality among wood surfaces. Surface coatings, such as oil and varnish, and thermal modification induced a change in the tactile warmth of wood. In pine and birch, a decrease in the tactile warmth of the surface was readily perceived after surface densification. The results provide some insights into how materials could be selected, based on their warmth quality, to improve the thermal comfort of living spaces and suggesting that this could be achieved by the extensive use of wood.

The Maxwell paired comparison model under Bayesian paradigm using informative priors

In paired comparison (PC) experiments, items are judged on subjective criterion in order to decide which of the two objects is preferable. A new PC model is developed and analyzed under Bayesian framework using two informative priors – conjugate prior and Dirichlet prior. The hyperparameters are elicited through the prior predictive distribution approach. The proposed model is employed to analyze the preference data of brands of drinking water. We consider two data sets with the sample sizes of 5 and 35 to explore the small and large sample behaviors of the proposed model. It is observed that the proposed model is capable of retaining the underlying preference ordering in both small and large sample scenarios. The conclusions are based on elicited values of worth parameters, estimated preference probabilities, and Bayes factor.

Color quality evaluation of Chinese bronzeware in typical museum lighting.

A series of psychophysical experiments have been conducted to investigate the effect of light sources on the color appearance of Chinese bronzeware. Three groups of 30 observers were asked to evaluate a set of Chinese bronzeware under different light sources in three paired-comparison experiments-one group of observers for each experiment. The visual attributes of color preference, color comfort, color discrimination, and antiquity were scaled. A panel of seven light sources of 3000 K, with Duv values ranging from $ - {0}.{015}$-0.015 to 0.015, was used in Experiment 1. A second panel of seven light sources of 4000 K, with a similar range of Duv values, was used in Experiment 2. For Experiment 3, six light sources were chosen from Exps. 1 and 2, plus four lights of 2700 K, 3300 K, 3700 K, and 4300 K, with Duv values of zero. These experimental lights produced a constant illuminance of approximately 200 lux in a pair of viewing booths, and their color rendering indices were between 88 and 95. The results showed that the subjective judgments for color preference and color comfort were highly correlated while the whiteness of the lighting strongly influenced the perception of color preference, comfort, and discrimination. A light source of 4000 K with a Duv value of zero exhibited the best color preference and color comfort performance, while observers were found to show the greatest capability for color discrimination under a light source of 4000 K with a Duv value of $ - {0}.{015}$-0.015. In addition, the bronzeware appeared to have greatest antiquity when illuminated by a 3000 K light source with a Duv value equal to 0.005. Based on the psychophysical data, the performance of typical color quality metrics were also tested in relation to the four scaled visual attributes.

Masking data: a solution to social desirability bias in paired comparison experiments

This paper deals with the reduction of evasive answering bias in paired comparisons studies by providing a masking mechanism to the judges. Specifically, the Warner (1965) masking design is applied in the application of Bradley and Terry (1952) paired comparison model. For estimating the worth parameters and preference probabilities, Bayesian method of estimation is applied. To study the behavior of Bayes estimates and the effect of masking parameter, simulation study is performed. It is observed that the preference ordering is not disturbed when the number of judges is moderate to large. Also, the preference ordering is observed to be robust with respect to the extent of masking, when the number of judges is large. These findings are also supported by a numerical study using real data.

Colorimetric Observer Categories for Young and Aged Using Paired-Comparison Experiments

Observers with normal color vision have different color perceptions since their retinal cones have different spectral responses, especially when the color pairs are constituted by different primary colors. In order to categorize the color-matching functions (CMFs) for young and aged observers, seven devices with different primary colors were performed on the clustering of observers’ CMFs. Four CMFs were generated from Beijing Institute of Graphic Communication (BIGC) with paired-comparison color matching experiments based on five printed colors from young and aged observers performed under fluorescent light source (Experiment I). Besides, color comparison experiments based on three printed colors under light emitting diodes (LEDs) light source were also carried out (Experiment II). And then, the existing CMFs, including Commission Internationale de l’ Eclairage 1964 (CIE 1964), CIE 1989 standard deviate observer (CIE 1989 SDO), CIE 2006, Sarkar 1 to Sarkar 8, Asano 1 to Asano 10, BIGC 1 to BIGC 4 were tested with the results from Experiments I and II respectively. The results indicated that the visual data from young and aged observers had quite large discrepancies. When they viewed printed materials illuminated by fluorescent and LED light sources in a field of view larger than 10°, based on the standardized residual sum of squares (STRESS) values and the number of the observers contributed to the minimum STRESS values, two new CMFs were proposed to represent the young and aged observers who participated in our experiments.

Bayesian analysis of paired-comparison sound quality ratings.

This paper presents a method to analyze paired-comparison data including either binary or graded ordinal responses, with or without ties. The proposed method can use either of two classical choice models: (1) Thurstone case V, which assumes a Gaussian distribution of the sensory variables underlying listener decisions, or (2) the Bradley-Terry-Luce (BTL) model, which assumes a logistic distribution. The analysis method was validated using simulated paired-comparison experiments with known distributions of the sound-quality parameters in the simulated population from which "participants" were generated at random. The validation indicated that the Thurstone and BTL models give similar results close to the true values. The estimated credibility of a quality difference was slightly higher with the BTL model. The analysis results showed dramatically better precision when the response data included graded ordinal judgments instead of binary responses. Allowing tied responses also tended to improve precision. The method was also applied to data from a real evaluation of hearing-aid programs. The analysis revealed clinically interesting results with high statistical credibility, although the amount of test data was limited.

Optimal Designs for Second-Order Interactions in Paired Comparison Experiments with Binary Attributes

In applications often paired comparisons involving competing options of either full or partial profiles are used. For this situation, we introduce an appropriate model and derive optimal designs in the presence of second-order interactions when all attributes are dichotomous.

Personalized Motivation-supportive Messages for Increasing Participation in Crowd-civic Systems

In crowd-civic systems, citizens form groups and work towards shared goals, such as discovering social issues or reforming official policies. Unfortunately, many real-world systems have been unsuccessful in continually motivating large numbers of citizens to participate voluntarily, despite various approaches such as gamification and persuasion techniques. In this paper, we examine the influence of personalized messages designed to support motivation as asserted by the Self-Determination Theory (SDT). We designed a crowd-civic platform for collecting community issues with personalized motivation-supportive messages and conducted two studies: a pair-comparison experiment with 150 participants on Amazon's Mechanical Turk and a live deployment study with 120 university members. Results of the pair-comparison study indicate applicability of SDT's perspective in crowd-civic systems. While applying it in the live system surfaced several challenges, including recruiting participants without interfering with general motivations, the collected data exhibited similar promising trends.

Receptive Field Mechanism and Pupilary Light Reflex for the Assessment of Visual Discomfort

Discomfort glare is defined as glare that causes discomfort without necessarily impairing the vision of objects. Traditional glare metrics fail for non-uniform luminaires. As an alternative, visual discomfort is determined by a physiological model incorporating the centre­surround receptive field mechanism and the pupillary light reflex. The pupil area, controlled by the pupillary light reflex, regulates the retinal illuminance. A centre-surround receptive field, described by a difference of Gaussians, represents the visual signal. The centre excites the signal whereas the surround controls the inhibition. A forced choice paired comparison experiment involves 7 non-uniform rear projected stimuli with different spatial frequencies. Inspired by a promising coefficient of determination of 0.90, the model is a candidate to replace current glare metrics as UGR or VCP, especially when non­uniform luminaires are to be evaluated.

The appreciation of LED-based white light sources by Dutch and Chinese people in three application areas

The aim of this study was to evaluate differences in appreciation for LED-based white-light sources between Dutch and Chinese people, when used for the illumination of three applications: fresh food, packaging material and skin tone. Furthermore, the contribution of the CIE special and general colour rendering indices ( Ri and Ra), a colour gamut measure ( Ga), and chroma changes for specific test-colour samples to perceived attractiveness was investigated. Thirty-four Dutch and 36 Chinese people assessed the attractiveness of the object appearance, with paired comparison experiments, for seven light sources at two CCT settings, 3000 K (Dutch and Chinese) and 4000 K (Chinese only), and a range of Ra and Ga values. It was found that for illuminating fresh food and packaging material, most Dutch and Chinese participants preferred light settings with an increased colour gamut. In contrast to colour rendering indices, the chroma change for the strong red test colour sample could be used to predict object attractiveness, but the established equations were different per application and culture. There was no clear relation between objective measures and skin tone preference for the Dutch study. Finally, Chinese participants did not like an increase in red saturation at 3000 K, but they allowed an increase at 4000 K.

Bayesian modeling to paired comparison data via the Pareto distribution

A probabilistic approach to build models for paired comparison experiments based on the comparison of two Pareto variables is considered. Analysis of the proposed model is carried out in classical as well as Bayesian frameworks. Informative and uninformative priors are employed to accommodate the prior information. Simulation study is conducted to assess the suitablily and performance of the model under theoretical conditions. Appropriateness of fit of the is also carried out. Entire inferential procedure is illustrated by comparing certain cricket teams using real dataset.

Pupillary light reflex, receptive field mechanism and correction for retinal position for the assessment of visual discomfort

Light sources causing annoyance or pain produce discomfort glare. Traditional glare metrics fail for non-uniform luminaires. As an alternative, visual discomfort is determined by a model incorporating the centre–surround receptive field mechanism, the pupillary light reflex and a correction for retinal position. The pupil area, controlled by the pupillary light reflex, regulates the retinal illuminance. A centre–surround receptive field, described by a difference of Gaussians, represents the visual signal. A correction according to the Guth position index accounts for the reduction in brightness perception when a light source is moved away from the line of sight. The model is analysed with a forced choice paired comparison experiment involving 17 non-uniform rear projected stimuli with different spatial frequencies and luminance steps. A coefficient of determination of 0.68 between the subjective assessment and the model is obtained. A paired comparison office luminaire experiment and a magnitude estimation experiment involving diffusor luminaires validate the model resulting in a coefficient of determination of 0.86 and 0.81, respectively. By including the pupillary light reflex, receptive field mechanism and a correction for retinal position, the more physiologically justified model is a promising alternative to current, often empirical, glare metrics, especially for non-uniform luminaires.

Paper: Expert Viewers' Preferences for Higher Frame Rate 3D Film

Recently the movie industry has been advocating the use of frame rates significantly higher than the traditional 24 frames per second. This higher frame rate theoretically improves the quality of motion portrayed in movies, and helps avoid motion blur, judder and other undesirable artifacts. Previously we reported that young adult audiences showed a clear preference for higher frame rates, particularly when contrasting 24 fps with 48 or 60 fps. We found little impact of shutter angle (frame exposure time) on viewers' choices. In the current study we replicated this experiment with an audience composed of imaging professionals who work in the film and display industry who assess image quality as an aspect of their everyday occupation. These viewers were also on average older and thus could be expected to have attachments to the "film look" both through experience and training. We used stereoscopic 3D content, filmed and projected at multiple frame rates (24, 48 and 60 fps), with shutter angles ranging from 90&#xB0; to 358&#xB0;, to evaluate viewer preferences. In paired-comparison experiments we assessed preferences along a set of five attributes (realism, motion smoothness, blur/clarity, quality of depth and overall preference). As with the young adults in the earlier study, the expert viewers showed a clear preference for higher frame rates, particularly when contrasting 24 fps with 48 or 60 fps. We found little impact of shutter angle on viewers' choices, with the exception of one clip at 48 fps where there was a preference for larger shutter angle. However, this preference was found for the most dynamic "warrior" clip in the experts but in the slower moving "picnic" clip for the na&#xEF;ve viewers. These data confirm the advantages afforded by high-frame rate capture and presentation in a cinema context in both na&#xEF;ve audiences and experienced film professionals. &#xA9; 2016 Society for Imaging Science and Technology.