Tal Shavit
College of Management Academic Studies
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Publication
Featured researches published by Tal Shavit.
Journal of the Operational Research Society | 2008
Uri Ben-Zion; Yuval Cohen; Ruth Peled; Tal Shavit
This paper investigates repetitive purchase decisions of perishable items in the face of uncertain demand (the newsvendor problem). The experimental design includes: high, or low profit levels; and uniform, or normal demand distributions. The results show that in all cases both learning and convergence occur and are effected by: (1) the mean demand; (2) the order-size of the maximal expected profit; and (3) the demand level of the immediately preceding round. In all cases of the experimental design, the purchase order converges to a value between the mean demand and the quantity for maximizing the expected profit.
Journal of Economic Psychology | 2001
Tal Shavit; Doron Sonsino; Uri Ben-Zion
Abstract We report the results of an experiment in which 135 students were asked to bid buying prices for five simple lotteries. 65 subjects were asked to complete the evaluation forms in class; the other 70 subjects were asked to complete the questionnaire within 24 hours on the Web. The subjects for both groups were carefully selected to avoid a possible selection-bias. The main results are: (1) bids on the Web are significantly higher than bids in class; (2) the standard deviations of the bids are significantly higher on the Internet. We also find some differences across gender in the response to the electronic medium. Our results suggest that subjects “risk aversion” might be lower on the Web and that the Internet medium might increase the noise in experimental data.
Journal of the Operational Research Society | 2010
Uri Ben-Zion; Yuval Cohen; Tal Shavit
AbstractNewsvendor theory assumes that the decision-maker faces a known distribution. But in real-life situations, demand distribution is not always known. In the experimental study which this paper presents, half of the participants assuming the newsvendor role were unaware of the underlying demand distribution, while the other half knew the demand distribution. Participants had to decide how many papers to order each day (for 100 days). The experimental findings indicate that subjects who know the demand distribution behave differently to those who do not. However, interestingly enough, knowing the demand distribution does not necessarily lead the subject closer to the optimal solution or improve profits. It was found that supply surplus at a certain period strongly affects the order quantity towards the following period, despite the knowledge of the demand distribution.
Journal of Behavioral Finance | 2009
Uri Ben-Zion; Sharon Shafran; Tal Shavit
This paper experimentally examines the behavior of investors when buying and selling stocks. This behavior was tested under different conditions, among them restrictions on asset holdings or different information conditions. Basic financial theory suggests that subjects buy and sell according to expectations regarding the future prices of assets. On the other hand, behavioral biases, such as the disposition effect, suggest that subjects are affected by past performance of assets. In a series of experiments, subjects were asked to allocate a given endowment among six assets. All the assets had the same normal distribution with positive mean. The results show no disposition effect in the simple case with no restrictions. A reverse disposition effect was found in case 2, where subjects were required to hold only three assets and change one asset on each round. However, when subjects received information on the market return each period, they showed disposition effect when gain and losses are measured relatively to the market. We explain these results by the disappointment effect and momentum trading behavior. The main contribution of the current research is to demonstrate that the disposition effect or momentum behavior can be a product of trading conditions.
Ageing & Society | 2012
Arie Sherman; Tal Shavit
ABSTRACT We suggest two supplements to Franco Modiglianis lifecycle model in order to explain why people who have retired from paid work choose either to start volunteering or increase the amount of time they devote to volunteer work. First, total consumption consists of both the material and immaterial products of work. While people can save their income in order to maintain an even level of material consumption, they unable to save a portion of the immaterial product. Second, at the statutory retirement age people retire only from paid work. We argue that older people substitute paid work for volunteering due to their inherent need to maintain immaterial consumption during retirement.
Gynecological Endocrinology | 2015
Einat Shalom-Paz; Saja Anabusi; M. Michaeli; Etti Karchovsky-Shoshan; Nechami Rothfarb; Tal Shavit; A. Ellenbogen
Abstract Objective: Spermatozoal morphology was reported to effect fertilization, embryo quality and pregnancy results in spontaneous conception and ART. Intracytoplasmic morphologically selected sperm injection (IMSI) is an innovative, not invasive technique, which examines the sperm with no harm at a magnification of 6000 × in order to obtain optimal sperm to perform IVF–ICSI. We evaluated the efficiency of IMSI technique in patients with repeated IVF–ICSI failure of at least three cycles with no viable pregnancy and/or very poor sperm quality. Study design and methods: All couples who performed IMSI between the years 2009 to 2012 were enrolled retrospectively to the study. Couples with male infertility who were treated with IMSI were included in the study. All their treatments were evaluated and divided into two subgroups: conventional IVF–ICSI treatment and their subsequent IMSI treatment. Demographic data, clinical parameters and outcome were recorded. The IMSI treatments were compared to previous non-IMSI treatments in terms of fertilization rates, cleavage rates, number of embryos and their quality, number of embryos transferred and pregnancy outcome. Main results: Forty-two couples were reviewed. Basic characteristics of the groups were comparable. Fertilization and cleavage rates of the two groups were comparable. The embryos quality demonstrated a trend toward superior quality (grade 1–2) embryos in the IMSI versus ICSI (60% versus 47%; p = 0.07 and 53% versus 40%; p = 0.07), respectively. Implantation and clinical pregnancy rates were significantly superior in IMSI group (19.2% versus 7.8%; p = 0.042 and 41.3% versus 10.5%; p = 0.02, respectively). Miscarriage rate was significantly higher in conventional IVF–ICSI group (100% versus 15.8%; p = 0.04), and live birth rate was significantly higher in IMSI group (0 in conventional IVF–ICSI and 34.7% per transfer in IMSI group; p = 0.003). Conclusion: IVF outcome of IMSI resulted in a higher implantation rate, pregnancy rate and most importantly delivery rate compare to non IMSI treated cycles.
European Journal of Obstetrics & Gynecology and Reproductive Biology | 2014
Tal Shavit; A. Ellenbogen; M. Michaeli; E. Kartchovsky; O. Ruzov; Einat Shalom-Paz
OBJECTIVE Patients with polycystic ovarian syndrome (PCOS) are at increased risk of ovarian hyperstimulation syndrome (OHSS) in controlled ovarian hyperstimulation cycles. Interventions to reduce the risk of OHSS in these patients include in-vitro fertilization (IVF) with a gonadotropin-releasing hormone (GnRH) antagonist, and retrieval of immature oocytes followed by in-vitro maturation (IVM). The aim of this study was to compare the outcomes of IVM and IVF-GnRH antagonist protocols in women with PCOS undergoing assisted reproductive technology. STUDY DESIGN Retrospective cohort study. Records of women with PCOS who underwent IVM or IVF-GnRH antagonist protocols between 2010 and 2011 were reviewed. In total, there were 61 IVM cycles and 53 IVF-GnRH antagonist cycles. The treatment protocols were compared in terms of the number of oocytes retrieved, dose of gonadotropin administrated, fertilization rates, quality of embryos, pregnancy, and delivery and abortion rates. RESULTS The number (mean±standard deviation) of mature oocytes did not differ significantly between the two groups (7.11±5.7 vs 8.16±5.07 for the GnRH antagonist group and the IVM group, respectively; p=0.38). The average dose of gonadotropin (1938 IU±838 IU/cycle vs 118±199 IU/cycle; p<0.001), fertilization rate (77% vs 60%; p<0.001) and high-quality embryo rate (58.8% vs 48.3; p<0.001) were significantly higher in the GnRH antagonist group compared with the IVM group. Pregnancy rates (40% vs 25%; p=0.08), livebirth rates per pregnancy (71% vs 53%; p=0.265) and abortion rates (10% vs 27%; p=0.17) were comparable. CONCLUSIONS The IVM protocol can be an alternative for infertile women with PCOS who wish to prevent the potential adverse effects of gonadotropin treatment. Prospective studies are needed to compare the outcomes of these two treatment protocols.
Review of Social Economy | 2010
Miki Malul; Tal Shavit
Abstract Trust and ethnic diversity are important variables that may impact and explain different economic decisions. This paper presents theoretical models accompanied by a survey that deals with the relation between mistrust and risky economic activity (e.g., the postponement of receiving and paying for a risky asset). Using the theoretical models and surveys as a basis, we suggest that subjective discount rates and bids for a lottery can be used to measure levels of mistrust. The surveys are used to measure the level of mistrust between the Israeli majority (Jews) and minority groups (Israeli Arabs, Bedouins, and Palestinians), and between Israeli Jews from different districts. Based on the survey results we demonstrate the theoretical implications of the effect of mistrust (MT) on economic growth and resource allocation between the majority and minorities. We conclude that MT leads to inefficient resource allocation, which subsequently leads to low economic growth rates.
American Journal of Obstetrics and Gynecology | 2012
Elad Mei-Dan; Ofer Fainaru; Shay Hantisteanu; Tal Shavit; A. Ellenbogen; Mordechai Hallak
OBJECTIVE To determine whether proangiogenic immature myeloid cells are present in human placentas. STUDY DESIGN Biopsies were obtained from 61 placentas of term pregnancies. Percentage of CD45(+)CD33(+)LIN2(-)HLADR(-) immature myeloid cells of total CD45(+) hematopoietic cells was determined by flow cytometry. Location of immature myeloid cells in the placenta was identified using confocal microscopy. The proangiogenic potential of immature myeloid cells was analyzed by endothelial tube formation. RESULTS Immature myeloid cells comprise ∼25% of human placental CD45(+) hematopoietic cells and infiltrate placentas in proximity of blood vessels. The percentage of immature myeloid cells correlated positively with placental weight (r(2) = 0.108, P = .01) and birthweight (r(2) = 0.087, P = .02). Endothelial tube formation was increased in the presence of immature myeloid cells as compared with the presence of CD45(+)LIN2(+) control cells. CONCLUSION Human placentas are populated by immature myeloid cells in the proximity of blood vessels. Consistent with their involvement in angiogenesis, immature myeloid cells accelerated endothelial tube formation. The presence of immature myeloid cells in pathologic pregnancies warrants further studies.
Applied Financial Economics Letters | 2006
Tal Shavit; Shosh Shahrabani; Uri Ben-Zion
Recent studies have questioned the existence and interpretation of a possible gap between Willingness-To-Pay (WTP) and Willingness-To-Accept (WTA). The study analyses the bidding patterns in buying and selling lottery tickets that represent financial assets using second price auction, and then tests for the existence of the WTP and WTA gap. It is shown that for lotteries, this gap is not significant for the group of all subjects, but that it may exist for a sub-group of subjects. Subjects were classified according to their degree of competitiveness and a negative gap was found for non-competitive subjects and a positive gap for competitive subjects. These gaps offset each other when the group of all the subjects was used.