Ely Dahan’s research while affiliated with University of California, Los Angeles and other places

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Publications (37)


Comparison of Rating Scale, Time Tradeoff, and Conjoint Analysis Methods for Assessment of Preferences in Prostate Cancer
  • Article

September 2019

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50 Reads

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6 Citations

Medical Decision Making

Robert M. Kaplan

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Ely Dahan

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Background. Conjoint analysis is widely used in studies of consumer preference but has only recently been applied to measure patient utilities for health outcomes. We compared the reliability, feasibility, and internal and predictive validity of conjoint scaling methods against better established rating scale and time tradeoff methods for assessing prostate cancer utilities in men at risk for prostate cancer. Methods. In total, 194 men who were biopsy negative for prostate cancer were randomly assigned to complete 2 preference assessment modules, either conjoint analysis and a rating scale module or conjoint analysis and a time tradeoff module. Each participant’s most important attribute was identified and evaluated in relation to age group (age <65, age 65 and older), education (high school, some college, college graduate), race/ethnicity (white, black, Latino), and relationship status (in significant relationship v. not). The methods were also evaluated in terms of ease of use and satisfaction. Results. Rating scales were rated as easiest to use and respondents were more satisfied with rating scales and conjoint in comparison to time tradeoffs. Rating scales and conjoint measures demonstrated significantly higher internal validity compared to time tradeoff when evaluated through R ² of the fitted utility function. The 3 methods were similar in terms of predictive validity, but conjoint analysis outperformed the rating scale method when patients were presented with novel combinations of attribute levels (68% correct v. 43%, P = 0.003). Conclusions. Rating scales and conjoint analysis exercises offer greater ease of use and higher satisfaction when measuring patient preferences in men biopsied for prostate cancer in comparison to time tradeoff exercises. Conjoint analysis may be a more robust approach to preference measurement for men at risk for prostate cancer.


Does Patient Preference Measurement in Decision Aids Improve Decisional Conflict? A Randomized Trial in Men with Prostate Cancer

June 2017

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53 Reads

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25 Citations

The Patient Patient-Centered Outcomes Research

Background Shared decision making (SDM) has been advocated as an approach to medical decision making that can improve decisional quality. Decision aids are tools that facilitate SDM in the context of limited physician time; however, many decision aids do not incorporate preference measurement. Objectives We aim to understand whether adding preference measurement to a standard patient educational intervention improves decisional quality and is feasible in a busy clinical setting. Methods Men with incident localized prostate cancer (n = 122) were recruited from the Greater Los Angeles Veterans Affairs (VA) Medical Center urology clinic, Olive View UCLA Medical Center, and Harbor UCLA Medical Center from January 2011 to May 2015 and randomized to education with a brochure about prostate cancer treatment or software-based preference assessment in addition to the brochure. Men undergoing preference assessment received a report detailing the relative strength of their preferences for treatment outcomes used in review with their doctor. Participants completed instruments measuring decisional conflict, knowledge, SDM, and patient satisfaction with care before and/or after their cancer consultation. Results Baseline knowledge scores were low (mean 62%). The baseline mean total score on the Decisional Conflict Scale was 2.3 (±0.9), signifying moderate decisional conflict. Men undergoing preference assessment had a significantly larger decrease in decisional conflict total score (p = 0.023) and the Perceived Effective Decision Making subscale (p = 0.003) post consult compared with those receiving education only. Improvements in satisfaction with care, SDM, and knowledge were similar between groups. Conclusions Individual-level preference assessment is feasible in the clinic setting. Patients with prostate cancer who undergo preference assessment are more certain about their treatment decisions and report decreased levels of decisional conflict when making these decisions.


Example of a choice set from the PROSPECT study. Patients choose their most and least preferred health state from among the four health states.
Posterior mean relative attribute importance scores for each health state attribute for 14 men and for the population.
Plot of the −log(CPO-MVP)s on all health state attributes, the −log(CPO-UVP)s for specific attributes, and the −log(CPO-BVP)s for the bivariate combinations of attributes for urinary and sexual functioning for 121 patients. Patients with values of the outlier statistic in the upper 2.5th percentile are labeled with ID numbers.
Plot of the −log(CPO-SET)s calculated for each choice set presented to eight patients.
Attributes and attribute levels from the PROSPECT Study.

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A Bayesian hierarchical model for discrete choice data in health care
  • Article
  • Publisher preview available

April 2017

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134 Reads

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5 Citations

In discrete choice experiments, patients are presented with sets of health states described by various attributes and asked to make choices from among them. Discrete choice experiments allow health care researchers to study the preferences of individual patients by eliciting trade-offs between different aspects of health-related quality of life. However, many discrete choice experiments yield data with incomplete ranking information and sparsity due to the limited number of choice sets presented to each patient, making it challenging to estimate patient preferences. Moreover, methods to identify outliers in discrete choice data are lacking. We develop a Bayesian hierarchical random effects rank-ordered multinomial logit model for discrete choice data. Missing ranks are accounted for by marginalizing over all possible permutations of unranked alternatives to estimate individual patient preferences, which are modeled as a function of patient covariates. We provide a Bayesian version of relative attribute importance, and adapt the use of the conditional predictive ordinate to identify outlying choice sets and outlying individuals with unusual preferences compared to the population. The model is applied to data from a study using a discrete choice experiment to estimate individual patient preferences for health states related to prostate cancer treatment.

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The Voice of the Patient Methodology: A Novel Mixed-Methods Approach to Identifying Treatment Goals for Men with Prostate Cancer

October 2016

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50 Reads

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9 Citations

The Patient Patient-Centered Outcomes Research

Background: Many guidelines advocate the use of shared decision making for men with newly diagnosed prostate cancer. Decision aids can facilitate the process of shared decision making. Implicit in this approach is the idea that physicians understand which elements of treatment matter to patients. Little formal work exists to guide physicians or developers of decision aids in identifying these attributes. We use a mixed-methods technique adapted from marketing science, the 'Voice of the Patient', to describe and identify treatment elements of value for men with localized prostate cancer. Methods: We conducted semi-structured interviews with 30 men treated for prostate cancer in the urology clinic of the West Los Angeles Veteran Affairs Medical Center. We used a qualitative analysis to generate themes in patient narratives, and a quantitative approach, agglomerative hierarchical clustering, to identify attributes of treatment that were most relevant to patients making decisions about prostate cancer. Results: We identified five 'traditional' prostate cancer treatment attributes: sexual dysfunction, bowel problems, urinary problems, lifespan, and others' opinions. We further identified two novel treatment attributes: a treatment's ability to validate a sense of proactivity and the need for an incision (separate from risks of surgery). Conclusions: Application of a successful marketing technique, the 'Voice of the Customer', in a clinical setting elicits non-obvious attributes that highlight unique patient decision-making concerns. Use of this method in the development of decision aids may result in more effective decision support.



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Marketing’s roles in innovation in business-to-business firms: Status, issues, and research agenda

December 2013

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3,922 Reads

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50 Citations

Marketing Letters

A project funded by the Institute for the Study of Business Markets to develop an understanding of the current state of business-to-business marketing and a research agenda for the field identified a lack of understanding of how the marketing function can or should best contribute to firms’ innovation efforts as the top priority. A workshop of senior academics and research-oriented practitioners explored this topic further, identifying four specific themes: (1) improving customer needs understanding and customer involvement in developing new products, (2) innovating beyond the lab, (3) disseminating and implementing research findings in firms, and (4) marketing’s overall role in innovation. This article defines these themes, sketches the current status of knowledge about each theme, frames practitioners’ issues with them, and proposes research agendas for each theme to move the field forward. The goal is to encourage rigorously executed academic research that can also help firms innovate more successfully.


TREATMENT PREFERENCES DERIVED USING ADAPTIVE BEST-WORST CONJOINT (ABC) ANALYSIS

October 2012

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41 Reads

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2 Citations

Purpose: We apply a newly developed preference measurement method, Adaptive Best-worst Conjoint (ABC), to improve questioning efficiency for patient treatment preferences. With this approach, utility functions with 7-10 parameters are estimated instantaneously at the individual level with as few as 12-15 tasks completed in 10 minutes. Method: Conjoint analysis respondents choose the best and worst of four treatment alternatives (attribute bundles). The method adaptively presents the next four treatment alternatives, and after 12-15 tasks a utility function is estimated and an individualized report is printed. This report summarizes the patient's treatment preferences and priorities, and serves to enhance the doctor-patient discussion of possible treatments. Adaptive Best-worst Conjoint with four options-at-a-time identifies five of the six possible paired comparisons (Best > option B, Best > option C, Best > Worst, option B > Worst, option C > Worst; only B is not compared to C). So ABC is 66% more efficient than traditional choice-based conjoint even without adaptive questioning. This inherent efficiency advantage of best-worst questioning is further enhanced through adaptive questioning based on transitivity of preference. That is, we assume that if full-profile A is preferred to full-profile B, and if B > E, then A is also > E, even though we never directly compared A to E. Such transitivity may resolve even more paired comparisons than direct questioning. For example, with 16-full-profiles, there are 16 x 15 / 2 = 120 possible paired comparisons, over 50% of which are resolved through transitivity. Results: The presentation highlights three key results: •Internal consistency: The estimated utility functions explain 88%, on average, of the variance in treatment scores. •Estimation and prediction: a comparison of linear regression, LINMAP, and Hierarchical Bayes shows that the abc method has high predictive accuracy (e.g., 68% first choice-out-of-four hit rate for holdout questions). Also, 80%-90% of paired comparisons in holdouts are consistent with the estimated utility function. •Respondent and physician reactionsto this system have been favorable as compared with a control group. Conclusion: Adaptive Best-worst Conjoint analysis compares favorably with Ratings Scale and Time Tradeoff as a way of measuring patient preferences. This presentation will lay out the Excel-based method as a direct takeaway from the SMDM conference.


IMPACT OF A NOVEL METHOD OF PATIENT PREFERENCE ELICITATION ON DECISION QUALITY IN MEN WITH PROSTATE CANCER: PILOT DATA

October 2012

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24 Reads

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3 Citations

The Journal of Urology

Purpose: Shared decision making can help men with localized prostate cancer make better informed decisions. A key component of shared decision-making is identification of patient preferences for outcomes of care. However, existing methods of patient preference assessment suffer from significant challenges to validity and feasibility. Conjoint analysis, a method of preference assessment taken from Marketing Science, has shown superior validity compared with existing methods in early testing. We report pilot patient satisfaction and decision quality data from a trial of conjoint analysis-based preference assessment in men with newly diagnosed prostate cancer Method: We developed a conjoint analysis application which allowed real time, individual level conjoint analysis. 30 men with incident localized prostate cancer were recruited in the West LA Veterans Affairs Urology Clinic and randomized to education with a brochure about prostate cancer treatment or preference assessment using conjoint analysis in addition to the brochure. Men underwent the intervention in the clinic prior to their cancer counseling session. Men undergoing values clarification received a report detailing the strength of their preferences for treatment attributes (such as sexual dysfunction) intended for review with their doctor. After the cancer consultation, men were surveyed with instruments measuring elements of decision quality and patient satisfaction with care. Result: Pilot data indicate a trend towards improved patient satisfaction in men who had preference assessment with conjoint analysis vs. those who did not. Mean scores on two patient satisfaction items differed significantly between cohorts, “Overall satisfaction with care” (1.3 vs 2.0, p<0.04) and “Thoroughness of main cancer practitioner” (1.1 vs 1.7, p<0.04). Pilot data showed a non-significant trend towards better scores in other items related to decision quality, such as decisional conflict, disease-specific knowledge, and measures of shared decision making. Conclusion: Individual-level, conjoint analysis-based preference assessment is feasible in the clinic setting. Pilot data indicate that prostate cancer patients who undergo values clarification with conjoint analysis felt more satisfied with their carel and that they perceived that the cancer practitioner counseling them was more thorough than men who did not. The latter finding may be explained by the use of the preference report that was used as a discussion point post values clarification


fIGuRE 3: Which Method Did Respondents Prefer: Survey or Stock Trading?
Preference Markets in New Product Development

November 2011

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830 Reads

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4 Citations

GfK Marketing Intelligence Review

Preference markets address the need for scalable, fast and engaging market research in new product development. The Web 2.0 paradigm, in which users contribute numerous ideas that may lead to new products, requires new methods of screening those ideas for their marketability and preference markets offer just such a mechanism. For faster new product development decisions, a flexible prioritization methodology for product features and concepts is tested. It scales up in the number of testable alternatives, limited only by the number of participants. New product preferences for concepts, attributes and attribute levels are measured by trading stocks whose prices are based upon share of choice of new products and features. Benefits of preference markets include speed, scalability, flexibility, and respondent enthusiasm for the method.


Figure 2: (8) Eight Crossover Vehicles 
Figure 3: Typical Product Information for Bike Pumps and Crossover Vehicles 
Figure 5: 
Figure 6: STOC Trading User Interface 
Securities Trading of Concepts (STOC) (Running title: SECURITIES TRADING OF CONCEPTS (STOC))

October 2011

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163 Reads

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1 Citation

Whitaker Foundation. The authors also wish to thank Rob Hardy of MIT and Limor Weisberg for their efforts in programming and designing many of the web sites that comprise this research. Market prices are well known to efficiently collect and aggregate diverse information regarding the value of commodities and assets. The role of markets has been particularly suitable to pricing financial securities. This article provides an alternative application of the pricing mechanism to marketing research- using pseudo-securities markets to measure preferences over


Citations (29)


... To determine appropriate attributes and levels, three treatment methods for localized prostate cancer were considered: active surveillance, radical prostatectomy, and radiation therapy. Based on a literature review [10][11][12][13][14][15], and consultations with urologists, oncologists, and patients, the following attributes were selected: risk of erectile dysfunction; risk of urinary incontinence; return to normal activities; other sides effects and transport to the hospital. An overview of the attributes and their levels are presented in Table 1. ...

Reference:

QUANTITATIVE METHODS FOR MEASURING PATIENT PREFERENCES: PILOT STUDY FOR PATIENTS WITH LOCALIZED PROSTATE CANCER
Comparison of Rating Scale, Time Tradeoff, and Conjoint Analysis Methods for Assessment of Preferences in Prostate Cancer
  • Citing Article
  • September 2019

Medical Decision Making

... Shared decision making (SDM) represents a shift from paternalistic practice to active engagement of the patient with the physician [1]. It aims to achieve high quality treatment decisions trough the sharing of knowledge between patient and their healthcare provider, whenever multiple options are considered clinically acceptable [2,3]. It looks to improve que quality of medical decisions by helping patients choose options, delay or forego care altogether, concordant with their values and in accordance with the best available scientific evidence [2]. ...

Does Patient Preference Measurement in Decision Aids Improve Decisional Conflict? A Randomized Trial in Men with Prostate Cancer
  • Citing Article
  • June 2017

The Patient Patient-Centered Outcomes Research

... A disaggregate choice model like the random parameter logit is generally better since it captures the heterogeneity among individuals or between groups. Another development in the theory of discrete choice estimates the model parameters at a group or individual level by using the latent class as implemented in the previous research (Dillingham et al., 2018;Goossens et al., 2014) and hierarchical Bayes (Antonio et al., 2018;Mohammadi, 2020). ...

A Bayesian hierarchical model for discrete choice data in health care

... Such research includes studies by Lim et al., 9 who used photo elicitation in semi-structured interviews and grounded theory to examine the perspectives of a sample of patients with multiple chronic conditions. Saigal et al. 10 used interviews and agglomerative hierarchical clustering to identify relevant treatment aspects for patients with prostate cancer. The nominal group technique was used by Col et al. 11 to elicit the treatment goals of multiple sclerosis patients. ...

The Voice of the Patient Methodology: A Novel Mixed-Methods Approach to Identifying Treatment Goals for Men with Prostate Cancer
  • Citing Article
  • October 2016

The Patient Patient-Centered Outcomes Research

... PM was developed using game mechanics for long-term consumer engagement as a low-cost and scalable digital crowdsourcing tool in order to collect information[13]. PM is inspired from Prediction Markets[14]and stock markets[15]in order to link new product features and concepts with contracts and to identify the most promising new product opportunities by trading those contracts. ...

Preference Markets in New Product Development

GfK Marketing Intelligence Review

... A group including volunteer customers evaluates technical drawings or high-resolution of product designs to elicit responses for the different product designs as indicated by existing literature (Dahan and Srinivasan 2000). Images of product designs with equal sizes are shown to volunteer customers. ...

The Predictive Power of Internet-Based Product Concept Testing Using Visual Depiction and Animation
  • Citing Article
  • March 2000

Journal of Product Innovation Management

... Our final sample was 20; we stopped participant recruitment when no new themes emerged-thematic saturation. 25 In addition, researchers' anecdotal data collection experience from previous studies 26 were considered to estimate a budget, which was not exceeded. Recruitment of both Spanish-speaking (n = 12) and English-speaking (n = 8) men occurred concurrently in order to obtain a relatively balanced sample. ...

IMPACT OF A NOVEL METHOD OF PATIENT PREFERENCE ELICITATION ON DECISION QUALITY IN MEN WITH PROSTATE CANCER: PILOT DATA
  • Citing Conference Paper
  • October 2012

The Journal of Urology

... It requires patients to make a series of trade-offs between competing options for treatment, or in this case, competing stressors ( Fig. 1 shows an example of a CA trade-off task). In order to help patients clarify their priorities [37], we used a form of CA called adaptive best-worst CA [26,38]. ...

TREATMENT PREFERENCES DERIVED USING ADAPTIVE BEST-WORST CONJOINT (ABC) ANALYSIS
  • Citing Conference Paper
  • October 2012

... Specifically, through the use of marketing intelligence, companies support new product development (Comai and Bogers, 2023) and take the important step of adding value to open innovation, especially in the inbound process. Not surprisingly, marketing can be an important partner in the innovation project, for example, through the provision of customer insights (Griffin et al., 2013). In conclusion, this paper proposes practical strategies for leveraging marketing intelligence to bolster open innovation processes, drawing from both theoretical insights and empirical examples. ...

Marketing’s roles in innovation in business-to-business firms: Status, issues, and research agenda

Marketing Letters