We investigate the theoretical possibility and empirical regularity of two troublesome anomalies that frequently arise when cross-price elasticities are estimated for a set of brands expected to be substitutes. These anomalies are the occurrence of: (a) negatively signed cross-elasticities; and (b) sign asymmetries in pairs of cross price elasticities. Drawing upon the Slutsky equation from neoclassical demand theory, we show how and why these anomalies may occur when cross elasticities are estimated for pairs of brands that are substitutes. We empirically examine these issues in the context of the widely used Multiplicative Competitive Interaction (MCI) and Multinomial Logit (MNL) specifications of the fully extended attraction models (Cooper and Nakanishi 1988). Utilizing a database of store-level scanner data for 25 categories and 127 brands of frequently purchased branded consumer goods, we find that about 18% of a total of 732 cross elasticity estimates are negative and approximately 40% of the 366 pairs of cross elasticities are sign asymmetric. Finally, we find that the occurrence of negatively signed cross elasticities can be partially explained by a set of hypothesized relationships between cross-price elasticities and brand share and elasticities of income and category demand. * 1 I What is not well understood is how often and under what circumstances that negative cross elasticities arise. It is also not well known how this relation translates into

OBJECTIVES: Approximately one‐half of patients with an episode of major depression will have a recurrent episode during their lifetime. Recent studies indicate that approximately 20% of depressed patients are resistant to traditional antidepressant treatments. This study utilizes medical and prescription claims data from the 1995–1998 MarketScan® Databases to profile the characteristics and health care utilization of patients with treatment‐resistant depression. METHODS: Depression‐diagnosed patients with adequate antidepressant dosing and treatment duration are selected. Patients are classified as treatment‐resistant if they have switched/augmented their initial medication with other antidepressants twice, or if they have switched/augmented their initial medication and have claims for depression‐related hospitalizations or suicide attempts. Depression‐diagnosed patients meeting selection criteria but not classified as treatment‐resistant by the above criteria are used as a comparison group. RESULTS: Patients with treatment‐resistant depression are at least twice as likely to be diagnosed with bipolar disorder, at least 1.5 times as likely to be diagnosed with comorbid anxiety disorders, and at least 1.5 times as likely to be diagnosed with substance‐related disorders than the comparison group (p‐values <0.01). Patients with treatment‐resistant depression have 30% higher mean number of psychiatric diagnostic groupings (PDG) and 9% higher mean number of major diagnostic categories (MDC) than the comparison group (p‐values <0.01). Furthermore, patients with treatment‐resistant depression are at least twice as likely to be hospitalized (depression and non‐depression related), and have 41% more outpatient visits than the comparison group (p‐values <0.01). Finally, patients with treatment‐resistant depression use 2 to 3 times more psychotropic medications (in addition to antidepressants) than the comparison group (p‐values <0.01). CONCLUSIONS: Treatment‐resistant patients are higher utilizers of both depression‐related and general medical services. This finding underscores the importance of early identification and effective treatment of treatment‐resistant patients to prevent future depressive episodes and to mitigate health care utilization.

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Conclusions: These results suggest that the two groups different in symptomatology and temperamental aspects. In particular, female patients present an higher level of severity in symptomatology and in temperamental aspects for all dimensions temperamental. Male patients present character features significantly higher in all dimensions of Self directedness and reducted cooperativeness. Male patients present higher comorbidity for general medical condition.