Choice bundling, unpacked: Observed and predicted effects on intertemporal choice in an additive model of hyperbolic delay discounting

One method known to increase preference for larger, later rewards (LLRs) over smaller, sooner rewards (SSRs) is choice bundling, in which a single choice produces a series of repeating consequences over time. The present study examined whether effects of choice bundling on preference for LLRs: (1) increase with the number of rewards in the bundle (i.e., bundle size); (2) are independent of differences in reward magnitude between conditions; and (3) accord with predictions of an additive model of hyperbolic delay discounting, in which the value of a bundle of rewards can be expressed as the summed discounted value of all rewards in that bundle. Participants (N = 252) completed a choice task to assess valuation of monetary LLRs at bundle sizes of 1 (control), 3, and 9 rewards per choice (ascending/descending order counterbalanced). To control for the magnitude effect, the total reward amounts were held constant across conditions. Choice bundling significantly increased LLR preference (p < .001), with the largest effect observed at the largest bundle size. The descending bundle-size order produced significantly greater LLR preference than the ascending order (p < .05), although order did not significantly interact with bundle size. Difference scores between observed measures and those predicted by an additive model of hyperbolic discounting were small and not significantly different than zero, but were not equivalent to zero. Future research should investigate the clinical utility of choice bundling for reducing the maladaptive health behavior (e.g., substance use) with which delay discounting is associated.

Convex Optimization for Bundle Size Pricing Problem

We study the bundle size pricing (BSP) problem in which a monopolist sells bundles of products to customers and the price of each bundle depends only on the size (number of items) of the bundle. Although this pricing mechanism is attractive in practice, finding optimal bundle prices is difficult because it involves characterizing distributions of the maximum partial sums of order statistics. In this paper, we propose to solve the BSP problem under a discrete choice model using only the first and second moments of customer valuations. Correlations between valuations of bundles are captured by the covariance matrix. We show that the BSP problem under this model is convex and can be efficiently solved using off-the-shelf solvers. Our approach is flexible in optimizing prices for any given bundle size. Numerical results show that it performs very well compared with state-of-the-art heuristics. This provides a unified and efficient approach to solve the BSP problem under various distributions and dimensions. This paper was accepted by David Simchi-Levi, revenue management and market analytics.

Large-Scale Bundle-Size Pricing: A Theoretical Analysis

Can you sell multiple items by providing only prices for different sizes of bundles rather than the different possible combinations of them? In this paper, we provide a framework for understanding “bundle-size pricing” (or simply, BSP) where only a menu of bundle sizes and their corresponding prices are offered. Although BSP is commonly used across several industries, little is known about the optimal BSP policy in terms of sizes and prices, along with the theoretical properties of its profit. In this paper, we provide a simple and tractable theoretical framework to analyze the large-scale BSP problem where a multiproduct firm is selling a large number of products. We characterize the circumstances under which such policies perform well by studying the effect of various factors such as marginal cost or customers’ budget on the performance of BSP and identify possible causes of its inefficiency.

Improving Web user Experience by Adapting RWD

Responsive Web Design (RWD) is a design which focuses on responsively fitting in whatever device the website is accessed from. It involves writing code for all possible screen sizes and bundling them together. Hence when the website is accessed, the whole bundle alongside the code for all screen sizes are downloaded to the user’s device and acts responsively when the browser window is resized, or the mobile device is rotated to portrait or landscape orientation. RWD can provide a far better user experience than the other designs because it primarily focuses on the user experience. Despite the bundle size being large, this method has proved to be robust in providing a better user experience and has evolved with evolution of web technologies. Latest CSS Media Queries make it possible to even target devices with limited accuracy. CSS Media Queries form the fundamentals of RWD because it is the most used way of targeting devices with various screen sizes.

1245. Does Complexity of Infection Prevention Bundles Matter in Colorectal Surgery? A Systematic Review and Meta-Analysis

Background Surgical site infection (SSI) prevention bundles in colorectal surgery are common. The optimal bundle composition and impact of increasingly complex and resource-intensive bundled interventions on SSI remain unclear. Methods (1) A systematic review and meta-analysis of randomized and observational trials with pre-post implementation data for colorectal SSI prevention bundles to study their effect on superficial, deep, and organ-space SSI. (2) A meta-regression to determine whether the bundle size (number of different bundle elements) affects SSI. (3) A correlation analysis to identify individual bundle elements with greatest SSI reduction. We used the METAN, METAEFF, and METAREG packages in STATA SE 15 for analysis. Results We included 38 studies in the systematic review, and 29 studies (49,589 patients) in the meta-analysis. Bundle composition was highly variable, ranging from 3 – 13 guideline-recommended elements per bundle. Meta-analyses showed bundles to be associated with relative risk reductions of 43% for any SSI (RR 0.57 [95% CI 0.48–0.67]; 44% for superficial SSI (RR 0.56 [95% CI 0.42–0.75]; 33% for deep SSI (RR 0.67 [95% CI 0.45–0.98], and 37% for organ/space SSI (RR 0.63 [95% CI 0.49 – 0.81]). On meta-regression, bundle size, especially ≥10 elements, was significantly associated with SSI reduction for any SSI (P = 0.04) and for superficial SSI (P = 0.005). Individual bundle elements correlated with strongest SSI reductions were mechanical bowel prep combined with oral antibiotics (R = −0.68, P = 0.0028) and pre-operative chlorhexidine showers (R = −0.49, P = 0.04) for organ/space SSI. Protocols including separate instrument trays and glove ± gown change prior to surgical wound closure (R = −0.55, P = 0.009), and standardized postoperative wound dressing change at 48 hours (R = −30.59, P = 0.005) correlated with highest superficial SSI reductions. Conclusion Complex colorectal bundles with ≥10 clinical guideline-recommended prevention elements are associated with higher reductions in any SSI and in superficial SSI. Further research should evaluate how complex SSI prevention colorectal bundles can be implemented and sustained with high fidelity in the clinical setting in a cost-effective manner. Disclosures All authors: No reported disclosures.

Ena/VASP processive elongation is modulated by avidity on actin filaments bundled by the filopodia cross-linker fascin

Ena/VASP tetramers are processive actin elongation factors that localize to diverse F-actin networks composed of filaments bundled by different cross-linking proteins, such as filopodia (fascin), lamellipodia (fimbrin), and stress fibers (α-actinin). Previously, we found that Ena takes approximately threefold longer processive runs on trailing barbed ends of fascin-bundled F-actin. Here, we used single-molecule TIRFM (total internal reflection fluorescence microscopy) and developed a kinetic model to further dissect Ena/VASP’s processive mechanism on bundled filaments. We discovered that Ena’s enhanced processivity on trailing barbed ends is specific to fascin bundles, with no enhancement on fimbrin or α-actinin bundles. Notably, Ena/VASP’s processive run length increases with the number of both fascin-bundled filaments and Ena “arms,” revealing avidity facilitates enhanced processivity. Consistently, Ena tetramers form more filopodia than mutant dimer and trimers in Drosophila culture cells. Moreover, enhanced processivity on trailing barbed ends of fascin-bundled filaments is an evolutionarily conserved property of Ena/VASP homologues, including human VASP and Caenorhabditis elegans UNC-34. These results demonstrate that Ena tetramers are tailored for enhanced processivity on fascin bundles and that avidity of multiple arms associating with multiple filaments is critical for this process. Furthermore, we discovered a novel regulatory process whereby bundle size and bundling protein specificity control activities of a processive assembly factor.