We present a new dynamic auction for procurement problems where payments are bounded by a hard budget constraint and money does not enter the procurer's objective function.JEL D21, D44, D45, D82.

Multiplicative growth processes that are subject to random shocks often have an asymmetric distribution of outcomes. In a series of incentivized laboratory experiments we show that a large majority of participants either strongly underestimate the asymmetry or ignore it completely. Participants misperceive the outcome distribution's spread to be too narrow-band and they estimate the median and the mode to lie too close to the distribution's center, failing to account for the compound nature of average growth. The observed biases are measured irrespective to risk preferences and they appear under a variety of conditions. The biases are largely consistent with a behavioral model in which geometric growth is confused with linear growth. This confusion is a possible driver of investors' difficulties with real-world financial products like leveraged ETFs and retirement savings plans. JEL-Classification: C91, D03, D14, G02

Although no proven evidence exists for the use of drainage in primary total hip arthroplasty, such drainage is routinely used. This prospective, randomized study comprised 80 patients who underwent a non-cemented total hip arthroplasty using a minimally invasive anterolateral approach. Patients were divided into 2 groups of 40: group 1 underwent drainage treatment and group 2 underwent no drainage treatment. No selection of patients occurred by age, sex, or body mass index. Blood loss was not significantly different between groups 1 (mean blood loss, 0.9 L [range, 0.3-2.1 L]) and 2 (mean blood loss, 0.9 L [range, 0.3-2.4 L]) (P=.7). On postoperative day 1, patients who underwent drainage treatment reported significantly more pain at rest (P=.01) and under stress (P=.03). The same finding was observed on postoperative day 4 (at rest, P=.04; under stress, P=.02). The nonuse of drainage significantly reduced operative time by 72 seconds (P=.01). Patients without drainage treatment had significantly larger hematomas than patients with drainage (mean, 43.7 cm(2) [range, 0-343 cm(2)] vs mean, 40.1 cm(2) [range, 0-514 cm(2)], respectively) (P=.03). No clinically relevant benefits associated with the use of drainage were identified. The increased size of the hematoma was not reflected in patient comfort. The authors consider the use of drainage in primary total hip arthroplasty unnecessary.

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We present a new dynamic auction for procurement problems where payments are bounded by a hard budget constraint and money does not enter the procurer's objective function.JEL D21, D44, D45, D82.