A random reference model

We provide two nested models of random reference-dependent choice in which the reference point is endogenously determined by random processes. Random choice behavior is due to random reference points, even though, from the decision-maker’s viewpoint, choices are deterministic. Through a revealed preference exercise, we establish when and how one can identify the reference-dependent preferences and the random reference rule from observed choice data. We also present behavioral postulates that characterize the empirical content of our models. Lastly, we investigate an application of our model to Bertrand competition with differentiated product

Limited attention and status quo bias

We introduce and axiomatically characterize a model of status quo bias in which the status quo affects choices by both imposing psychological constraints and focusing attention. The resulting Limited Attention Status Quo Bias model can explain both the findings that status quo bias is more prevalent in larger choice sets and that the introduction of a status quo can change choices between non-status quo alternatives. Existing models of status quo bias are inconsistent with the former finding while models of decision avoidance are inconsistent with the latter. We show that the interaction of the two effects has important economic implications, and report the results of laboratory experiments which show that both attention and psychological constraints are necessary to explain the impact of status quo on choice

Aortic stifness in patients with rheumatoid Arthritis

Romatoid Artirit (RA) de mortalitenin en önemli sebebi kardiyovasküler sistem (KVS) tutulumudur. Aortun mekanik özelliklerinin invaziv olmayan yöntemlerle değerlendirilmesi aterosk-lerozun erken tanısında oldukça yararlıdır. Bu çalışmada; ateroskleroz gelişimine yol açabilecek başka hastalığı ve risk faktörleri olmayan RA'lı hastalarda aortun elastisite parametreleri ile hastalığın aktivite ölçümleri arasında etkileşim olup olmadığı araştırılmıştır. Yöntem: Çalışmaya 46 RA'li hasta ve 20 sağlıklı birey alındı. Hastaların hastalık süresi, DAS-28 skorları, eritrosit sedimentasyon hızı (ESH), C-reaktif proteinleri (CRP) ve lipid düzeyleri kaydedildi. Ekokardiyografik değerlendirme ile aortun elastik parametreleri hesaplandı ve gruplar arasında karşılaştırma yapıldı. RA'lı hastaların aktivite ölçümleri ile aortun elastik parametreleri arasındaki ilişki araştırıldı. Bulgular: RA'lı hastaların aortik strain ve distensibilite düzeyi; kontrol grubuna göre daha düşük bulundu (p<0.002). Aortik strain ile ESH arasında istatistiksel olarak ileri düzeyde anlamlı bir ilişki saptanmıştır (p<0.01). Distensibilite ile DAS28 ve ESH arasında istatistiksel olarak anlamlı bir ilişki bulundu (p<0.05). Sonuç: Ekokardiyografi ile noninvaziv metod olarak ölçülen aortik elastisite parametreleri hastalığın erken döneminde kardiyovasküler riski tahmin etmede faydalı olabilir.In patients with RA, the cardiovascular system involvement is the most important reason for the increase of mortality. Evaluation by non-invasive methods of mechanical properties of the aorta is quite useful in early diagnosis of atherosclerosis. In this study we have investigated that the relation between aortic elasticity parameters and the disease activity criteria in the RA patients who has not have any risk factors and any diseases leading to the development of atherosclerosis. Method: 46 RA patients and 20 healthy subjects were included in the study. The patients, disease duration and DAS-28 scores and ESR and CRP and lipid parametres results were recorded. Echocardiographic evaluation was performed and the aortic elastic parameters were calculated and compared between groups. Activity parameters of patients with RA and the relation between aortic elastic parameters were investigated. Results: Aortic strain and distensibilitiy levels of RA patients, were lower than the control group (p &lt;0.002). According to there is no statistically significant difference between patient and control groups. There is a statistically significant relationship between DAS28 and distensibilitiy (p &lt;0.05). And there is a statistically significant correlation between ESH and distensibility (p &lt;0.01). And there is advanced level of statistically significant correlation between strain and the ESH (p &lt;0.01). Conclusion: Aortic elasticity parameters measured by echocardiography as a noninvasive method may be useful to predict the risk of cardiovascular disease at early stages