Subjective Value Of Time Research Articles

Ridesourcing mode choice: A latent class choice model for UberX in Chile

As shared mobility expands, ridesourcing has become its most popular manifestation. However, users’ mode choice has not yet been sufficiently explored. Thus, this study aims to model ridesourcing mode choice across different latent classes to ascertain who chose ridesourcing and why.We conducted a mode choice study by collecting revealed preference surveys from UberX users in Viña del Mar, Chile, in 2017. We then determined the existence of two latent classes and modeled the mode choice using a latent class choice model. Ultimately, we characterized individuals belonging to each latent class and calculated the subjective value of time (SVT).Most UberX users were highly educated and aged 20–35 years. Further, UberX gained users principally from public transport (80%). Likewise, the two latent classes differed by socioeconomic characteristics and SVTs. A latent class grouped the highest-educated and highest-earning users, who also offered the highest SVT.In summary, two latent classes, differentiated by educational level and income, formed the ridesourcing market. Besides, they offered distinct ridesourcing choice behavior based on the widely dissimilar SVTs. There was also a strong substitution effect between ridesourcing and transit use. The results imply that policymakers and transportation planners could have increased the competitiveness of the public transit system by improving rapidity and safety, having room to increase the fares to defray the improvements. Further, they could have used information related to the latent classes to customize relevant policies and marketing strategies (routes, frequency, fares, etc.) for every latent class.

Optimal pricing of customized bus services and ride-sharing based on a competitive game model

Customized bus services and ride-sharing are two emerging online-hailing transport modes that greatly improve public transport efficiency and convenience, especially for night services. In this study we consider the optimal pricing problem for a platform providing these two service modes. Ride-sharing vehicles can be either driver- or platform-owned. We formulate a competitive game model in which the objective is to maximize the profits of each mode based on passengers’ transport mode choice, which is strongly affected by utility functions based on the passengers’ subjective value of time and the price of the transport mode. We develop a questionnaire to measure passengers’ subjective value of time and use the results to determine the relevant parameter value in the model. We then conduct a sensitivity analysis to study the effects of different parameters on the optimal prices and profits. The profits earned by both customized bus services and ride-sharing are positively correlated with the proportion of platform-owned vehicles. Furthermore, we conduct a series of simulation experiments to verify the validity of the numerical results. The results indicate that the absolute difference ratios between the simulation and numerical results are less than 1% when the number of passengers is set to over 8000.

ОБРАЗ МИРА КАК ПСИХОЛОГИЧЕСКАЯ СИСТЕМА И ЕГО ПРИРОДНО-СРЕДОВЫЕ ДЕТЕРМИНАНТЫ

The image of the world is considered as a psychological system that includes spatial-temporal and value-semantic dimensions. The theoretical analysis of the research problem allows us to state as follows. There is a contradiction between the significance of objective natural and geographical factors in the formation of a human's lifestyle, and the lack of knowledge of their influence on the formation of his subjective image of the world. The pur-pose of this article is to study the determination of subjective chronotopic characteristics of the human world image by objective environmental factors. The study involved 450 residents of 10 Russian cities that differ significantly in their natural and geographical features. The following characteristics of the respondents’ place of residence were evaluated: geographical latitude; the degree of discrepancy between the offi-cial time zone and the actual time set by geographical longitude; the average annual tempera-ture; the number of sunshine hours per year. The complex of psychodiagnostic methods included the author’s questionnaire of structure identity; the graphic test "Circles"; the scale of polychronous values; the scale of time value as an economic resource; the semantic differen-tial of time; the author’s methodology of studying value preferences; the test of life-meaning orientations. Natural and geographical features of the life environment determine significant diffe-rences in the spatial-temporal and value-semantic characteristics of the subjective image of the world. Representatives of the northern territories have a significant belonging to the modern generation, the semantic connectedness of the time perspective, and the subjective value of time. They see their present and future as about anxious and tense; they focus on the values of adaptation, as well as internality. Residents of warm regions have a more signi-ficant gender and family identity, semantic connectedness of the time perspective, anxiety of their present, orientation to the values of adaptation. If the officially set time goes ahead over the actual longitudinal time, it is correlated with the disturbing image of the present, the idea of saturation, brightness and iridescence of past and future, focus on the value of sociali-zation. The environmental characteristics of residence have a significant impact on the subjective image of reality. The greatest value among the considered determinants is the geographical latitude of the place of residence. The influence of environmental determinants on the subjec-tive parameters of the image of the world is indirectly related to the intermediate links such as economic and cultural type or psychophysiological characteristics of life activity in the corresponding natural conditions.

Classic and bayesian estimation of Subjective Value of Time

In this paper, we estimate different travel time components in an urban transport context in Bogota, by using discrete choice models. For the analysis, we evaluate two different approaches for model estimation: the maximum likelihood estimation (classical) and the Bayesian estimation, allowing a comparison between both approaches when are used to estimate the subjective value of time (SVT) as the marginal rate of substitution between time and cost. We found that the average SVT when we used the classical estimation is US$0.14/min; meanwhile, the access time was US$0.21/min and the penalty for a transfer is US$0.74. On the other hand, the average values estimated when using Bayesian approach were US$0.15/min for the SVT in vehicle, US$0.21/min for the access time and US$0.83 for the transfer penalty.

A Maximum Entropy Estimator for the Aggregate Hierarchical Logit Model

A new approach for estimating the aggregate hierarchical logit model is presented. Though usually derived from random utility theory assuming correlated stochastic errors, the model can also be derived as a solution to a maximum entropy problem. Under the latter approach, the Lagrange multipliers of the optimization problem can be understood as parameter estimators of the model. Based on theoretical analysis and Monte Carlo simulations of a transportation demand model, it is demonstrated that the maximum entropy estimators have statistical properties that are superior to classical maximum likelihood estimators, particularly for small or medium-size samples. The simulations also generated reduced bias in the estimates of the subjective value of time and consumer surplus.

Modeling drivers’ speed selection as a trade-off behavior

This paper proposes a new model of driver-preferred speeds derived from the assumption that drivers trade-off a portion of their safety for a time gain. The risk of receiving a ticket for speeding is also considered. A trip disutility concept is selected to combine the three components of speed choice (safety, time, and enforcement). The perceived crash risk and speed enforcement are considered as speed deterrents while the perceived value of a time gain is considered as a speed enticement. According to this concept, speeds that minimize the perceived trip disutility are preferred by drivers. The modeled trade-off behavior does not have to be fully rational since it is affected by drivers’ preferences and their ability to perceive the risk. As such, the proposed framework follows the concept of bound rationality. The attractiveness of the model lies in its parameters being estimable with the observed preferred speeds and then interpretable as the factors of risk perception, the subjective value of time, and the perceived risk of speed enforcement. The proposed method may successfully supplement behavioral studies based on a driver survey. The study focuses on four-lane rural and suburban roads in Indiana, USA. The behavior of two types of drivers (trucks and cars) is modeled. The selection of test sites was such that the roads and other local characteristics varied across the studied sites while the population of drivers could be assumed as the same. The density of intersections, land development along the road, and the presence of sidewalks were the identified prominent risk perception factors. Another interesting finding is that the speed limit seems to encourage slow drivers to drive faster and fast drivers to drive slower.

Illusion of Motion

This paper explores drivers’ subjective value of time under moving and stopped freeway travel conditions with a stated preference survey. Unlike previous studies that assumed a constant value of time, this research relates perceived satisfaction of a freeway trip to its quality indicators. Sixty-nine subjects in Minneapolis–St. Paul, Minnesota, were asked to rank 16 driving scenarios in four condition sets with different durations of ramp wait and freeway travel. Several utility functions were specified in which the weight of ramp delay was a function of the length of the delay and subject-specific variables; the resulting choice models were estimated with rank-ordered logit, binary logit, and rank-ordered mixed-logit techniques. Results suggest that drivers perceive ramp wait as more onerous than freeway travel. They also weight each minute of ramp wait more heavily as the delay increases. Subjects showed some tolerance to the first several minutes of ramp delay (less than 5 min) but perceived long delays as up to 12 times more onerous than time in motion. The derived weighting function for ramp wait can improve the design of freeway traffic control strategies that trade off freeway delay with ramp wait. The findings also enable a more utility-based approach for freeway operations than the current method, which has the engineering efficiency objective of minimizing total system delay or maximizing throughput. Minimizing total perceived travel time is probably more appropriate than minimizing total absolute travel time, which does not take into account driver acceptance. The weighting function can be easily transformed into a value-of-time function for project evaluation purposes.

Understanding suburban travel demand: Flexible modelling with revealed and stated choice data

We analyse the choice of mode in suburban corridors using nested logit specifications with revealed and stated preference data. The latter were obtained from a choice experiment between car and bus, which allowed for interactions among the main policy variables: travel cost, travel time and frequency. The experiment also included parking cost and comfort attributes. The attribute levels in the experiment were adapted to travellers’ experience using their revealed preference information. Different model specifications were tested accounting for the presence of income effect, systematic taste variation, and incorporating the effect of latent variables. We also derived willingness-to-pay measures, such as the subjective value of time, that vary among individuals as well as elasticity values. Finally, we analysed the demand response to various policy scenarios that favour public transport use by considering improvements in level-of-service, fare reductions and/or increases in parking costs. In general, demand was shown to be more sensitive to policies that penalise the private car than those improving public transport.

Analysing Demand for Suburban Trips: A Mixed RP/SP Model with Latent Variables and Interaction Effects

We analyse mode choice behaviour for suburban trips in the Grand Canary island using mixed revealed preference (RP)/stated preference (SP) information. The SP choice experiment allowed for interactions among the main policy variables: travel cost, travel time and frequency, and also to test the influence of latent variables such as comfort. It also led to discuss additional requirements on the size and sign of the estimated model parameters, to assess model quality when interactions are present. The RP survey produced data on actual trip behaviour and was used to adapt the SP choice experiment. During the specification searches we detected the presence of income effect and were able to derive willingness-to-pay measures, such as the subjective value of time, which varied among individuals. We also studied the systematic heterogeneity in individual tastes through the specification of models allowing for interactions between level-of-service and socio-economic variables. We concluded examining the sensitivity of travellers’ behaviour to various policy scenarios. In particular, it seems that contrary to political opinion, in a crowded island policies penalising the use of the private car seem to have a far greater impact in terms of bus patronage than policies implying direct improvements to the public transport service.

A semi-compensatory discrete choice model with explicit attribute thresholds of perception

Random utility models are typically based on the assumptions that individuals exhibit compensatory behaviour and that their choice sets are pre-specified. These assumptions may be unrealistic in many practical cases; in particular, it has been argued that thresholds may be part of choice–rejection mechanisms (i.e. if the threshold of any attribute for a given alternative is surpassed the alternative is rejected) and, therefore, act as explicit criteria to determine the set of feasible alternatives. We formulate a semi-compensatory two-stage discrete choice model incorporating randomly distributed thresholds for attribute acceptance. The formulation allows us to estimate the parameters of the threshold’s probability distribution; these parameters can be expressed as a function of the socio-economics characteristics of the individual and the conditions under which the choice process takes place. Applying the model to real and simulated data allowed us to conclude that if thresholds exist in the population, the use of compensatory models such as Multinomial Logit or even Mixed Logit, can lead to serious errors in model estimation and, therefore, in the computation of marginal rates of substitution such as the subjective value of time, as well as in prediction. Although the Mixed Logit model can deal with random parameters allowing to treat taste differences, we found it could not be used to accommodate non-compensatory behaviour or to represent the existence of thresholds.

Microeconomic Formulation and Estimation of a Residential Location Choice Model: Implications for the Value of Time

Abstract We formulate a microeconomic model of residential location choice behavior as an aggregate of the individual behaviors of household members, subject to individual time constraints and a common income budget. A simplified version of the model is estimated from stated preference rank‐order data, yielding a function that may be interpretated as a conditional indirect utility function. We consider Box‐Tukey transformations, segmentation by income class, and a consistent treatment of data at different rank depths using the simultaneous mixed‐estimation method. Measures of the household's willingness‐to‐pay (through rents) for reducing travel times to work and study in the short run, are interpreted as subjective values of time and compared with such values derived from mode choice models. Our results are plausible, and consistent with recent findings showing that the short‐run benefits of transport projects derived by transport models are larger than benefits measured at the land use system.

Valuing reductions in environmental pollution in a residential location context

A stated preference ranking experiment is designed to estimate the willingness-to-pay (WTP) for reducing the amount of atmospheric pollution in a group-based residential location context. Important issues are the proper definition of the context and the variable metric for the environmental attribute. Sample members were asked to rank 10 options arising from variations in the attributes travel time to work and to study, rent of the house and an environmental attribute (the number of days of Alert, in terms of concentration of PM 10, at a dwelling’s location). Multinomial logit models based on a consistent microeconomic framework were estimated for various stratifications of the data (income, pollution sensitivity, and type of dwelling currently inhabited). From these subjective values of time and WTP were derived for reductions in the number of days of alert and hence the amount of pollutant concentration at a given location. The WTP came out at about 1% of the family income for reducing one contingence day per year; this is approximately 60% higher than an estimate reported for the city of Edmonton, Canada, but the average PM 10 concentration in Santiago is about six times higher.

Differences in Subjective and Social Value of Time: Empirical Evidence from Traffic Study in Croatia

Estimating the value of time (VOT) in transport is primarily an empirical question, despite some strong theoretical foundations from microeconomics. The most common estimation approach has been based on discrete choice models, which produce estimates of the users’ subjective VOT. These estimates are often used as inputs into estimates of user benefits for economic appraisals. The subjective and social values are thought to be roughly equal, though several authors have analyzed the possibility of divergence between these two measures. How estimates of the subjective VOT can produce biased estimates of the social VOT is analyzed. The discussion starts with a conceptual basis for possible differences between subjective and social measures. In an empirical section, stated-preference and revealed-preference data from Croatia are analyzed. The results lend support to the hypothesis that the implied subjective VOT, as revealed by mode choice data, may in some instances be a poor approximation of the social VOT, in particular when travelers are not directly bearing the opportunity cost of their travel time.

Confidence intervals to bound the value of time

Abstract The derivation of a subjective value of time (SVT) requires finding the marginal rate of substitution between travel time and cost in a travel choice model. In the typical case of models with linear-in-parameters utility functions, the SVT is equal to the ratio between the parameters of travel time and cost. However, since model estimation yields an estimator of the true values of their parameters (with a certain probability distribution), the computed SVT is also an estimator with another probability distribution; then, it is important to devise a method to incorporate the randomness of the estimated SVT in project evaluation. In this paper, we consider this problem rigorously and propose methods to replace the typical SVT point estimates by the construction of confidence intervals for a certain probability level. This allows, in addition, to estimate the SVT limits (lower and upper) which may be used in sensitivity analyses of the calculation of project revenues in transport infrastructure investment. The paper proposes two forms for building these intervals: the t -test and the LR-test, and discusses the construction of intervals for Multinomial Logit (MNL), Hierarchical Logit (HL) and Box–Cox Logit (BCL) models. We use two samples where the values of the level-of-service attributes have been measured with an unusually high degree of precision. Other methods proposed in the literature are also studied (simulation of multivariate normal variates (MVNS), SVT normal approximation (NA), and re-sampling techniques) using the above data, and their advantages and disadvantages are analysed. In addition, the effects of different modelling elements on the size and quality of the constructed intervals are scrutinised, such as model specification, sample size and individual income. Finally, the proposed methods are compared and recommendations about the use of each one in practice are indicated.

Stated Preferences in Modelling Accessibility

The stated preference (SP) experimental design problem in measuring and representing the role of accessibility in modelling urban residential location is considered. The preferences of households between certain accessibility attributes and the monthly rent of the house, ceteris paribus with respect to the rest of the location attributes, is analysed in order to isolate the effects of interest. A review of the conceptual definition of accessibility, its relationship with the transportation system, its functionality and the different measures used up until now, allowed generation of an SP data collection instrument. This was employed to subject a sample of households to the location decision based on several transport system variables. The experiment made several novel contributions. First, the whole household was considered as the choice-making entity, with decisions shared by all its members. Second, the alternatives considered different accessibility levels without modifying the household's current location. Using the data gathered, models were estimated with consistent parameters in terms of their signs and significance tests, and some functional forms associated with the perception of the access concept were defined. Furthermore, a valuation of time index was generated and this allowed a new discussion to be opened regarding its relation to the subjective value of time traditionally derived from mode-choice models.

Mixed modelling of interurban trips by coach and train

A stated preference (SP) experiment for interurban trips by coach or train was designed and programmed on portable computers with the aid of specialized software. Trip characteristics and socio-economic information about each individual were also gathered. Four variables were considered: travel time, fare, comfort and reliability. Data for 112 individuals were collected, 14 of which always preferred train; this behaviour was attributed to safety and comfort reasons and therefore the latter were treated separately because of their peculiarity. The data for the remaining 98 cases had ten choices available for each individual; thus we had a final sample of 980 observations for the calibration stage. The next phase of the project was to add revealed preference (RP) data which came from two sources: that collected during the SP experiment (i.e. 98 individuals) and another sample taken as part of a previous research project conducted by the Universidad de Chile (407 individuals). The complete data set was used to examine several issues in the mixed estimation of RP/SP models, such as: appropriate model structure, structural variations between the estimation and forecasting stages (including the role of mode specific constants and inertia-like variables), and influence of the relative proportions of RP and SP data in the modelling results. Our findings, particularly in terms of subjective values of time, are compared with previous studies both in Chile and elsewhere.

The impact of temporal context and risk on the judged value of future outcomes

This study investigated (1) the impact of time frames on the subjective values of time or the discounting function, the discounting operation, and the response strategy used in two tasks, (2) scale convergence across risky and riskless investments for time and the value of outcomes, (3) the effect of continuous and categorical response formats on the subjects' judgments, and (4) the comparability of the discounting strategy used in rating and preference tasks. College students were asked to evaluate the desirability of risky investments that were presented in the context of a short time frame or a long time frame. All of the subjects judged risky investments during one session and indicated their strength of preference for riskless investments during the other session. Results indicated that the time frame manipulation affected the form of the discounting function. Although scale convergence was obtained for the interest rates across tasks, scale convergence did not occur for time. The subjective values for time, generated from the riskless investments, consistently exceeded the scale values obtained with the risky investments. The discounting functions for time were much steeper for the riskless investments than for the risky investments. For example, a $300 return from a riskless investment was discounted more, as a function of the time, than was a $300 return associated with risk. These results are discussed in relation to previous research and the implications for a general model of temporal discounting.

The Value of Time Spent in Price-Comparison Shopping: Survey and Experimental Evidence

The value that consumers place on time spent in price-comparison shopping is central to the economics of information theory and models of consumers' search behavior. Yet few empirical studies have examined consumers' subjective value of time. Building on Gary Becker's work, this article presents two tests of a model of the subjective value of time. In an effort to explain consumers' subjective value of time while they are price-comparison shopping, the model introduces perceived enjoyment of shopping as a new explanatory variable. The findings reveal that respondents incorporate both wage rates and perceived enjoyment of price-comparison shopping into their subjective value of time.

Subjective value of time in bus transit travel

A psychological scaling technique, magnitude estimation, is used to rate time spent on various elements of bus transit trips. Relative values of time are found for in-vehicle portions of trips, walking, waiting and transferring. Because magnitude estimation produces a ratio scale, results can be directly incorporated into modal choice analyses, route planning and evaluation procedures where monetary values of time are not necessarily required.