Optimal threshold analysis of segmentation methods for identifying target customers

In CRM (Customer Relationship Management), the importance of a segmentation method for identifying good customers has been increasing. For evaluation of different segmentation methods, Accuracy often plays a key role. This indicator,however, cannot distinguish the following two types of errors: Type I Error for misidentifying a good customer as a bad customer and Type II Error for misinterpreting a bad customer as a good customer. In order to analyze the financial effectiveness of various segmentation methods, it is crucial to capture the distinction between Type I and Type II Errors since the former represents the opportunity cost while the latter results in the inefficient use of the promotion budget. The purpose of this paper is to overcome this pitfall by introducing two different indicators: Recall and Precision, which have been prevalent in the area of Information Retrieval. A mathematical model is developed for describing a generic segmentation method. Assuming that a promotion is addressed exclusively to the selected target customers, the financial effectiveness of the underlying segmentation method is expressed as a function of Recall and Precision. An optimization problem is then formulated so as to maximize the financial measure by finding the optimal threshold level in terms of the severeness for estimating the target set of good customers. By introducing a functional form which represents correctness and mistakes about the target set, the unique optimal solution is derived explicitly. Using real customer purchase data, the proposed approach is validated where Logistic Regression Model and Support Vector Machine are employed as segmentation methods. The methodology developed in this paper may provide a foundation for understanding and comparing the performance characteristics of various segmentation methods from a new perspective

Tuberous Sclerosis 2 Gene Is Expressed at High Levels in Specific Types of Neurons in the Mouse Brain

Tuberous sclerosis (TSC) is an autosomal dominant disorder characterized by mental retardation, epilepsy and hamartomatous growth in many tissues. The gene (TSC2) encoding a tumor suppressor protein whose mutations cause TSC, has been demonstrated to be expressed at high levels in the adult and developing brain, raising the question of whether or not the TSC2 gene product has unique roles in differentiation related to cytoskeletal interactions within the central nervous system, in addition to a tumor suppressor function. To determine the expression of TSC2 in functionally distinct neuron types of the mouse brain, we carried out in situ hybridization with digoxigenin-labeled riboprobes for the detection of TSC2 mRNA. High levels of the TSC2 gene were in neurons of the pyramidal and dentate granular layer in the hippocampus, cerebellar Purkinje cells, neurons of the piriform cortex, motor neurons in the medulla and interneurons in the striatum, while intermediate levels were in cortical neurons, striatal neurons, septal neurons, thalamic neurons and neurons in the substantia nigra compacta. Thus, the high expression of the TSC2 gene has restricted distribution in specific neuronal types which are characterized by well-developed dendrites and rich in use-dependent long-term changes in synaptic efficacy. These results suggest that the function of the TSC2 gene product may be involved on a cellular basis in neuronal plasticity and relevant to mental retardation observed in TSC patients

Phosphate and Klotho

Klotho is a putative aging suppressor gene encoding a single-pass transmembrane co-receptor that makes the fibroblast growth factor (FGF) receptor specific for FGF-23. In addition to multiple endocrine organs, Klotho is expressed in kidney distal convoluted tubules and parathyroid cells, mediating the role of FGF-23 in bone–kidney–parathyroid control of phosphate and calcium. Klotho–/– mice display premature aging and chronic kidney disease-associated mineral and bone disorder (CKD-MBD)-like phenotypes mediated by hyperphosphatemia and remediated by phosphate-lowering interventions (diets low in phosphate or vitamin D; knockouts of 1α-hydroxylase, vitamin D receptor, or NaPi cotransporter). CKD can be seen as a state of hyperphosphatemia-induced accelerated aging associated with Klotho deficiency. Humans with CKD experience decreased Klotho expression as early as stage 1 CKD; Klotho continues to decline as CKD progresses, causing FGF-23 resistance and provoking large FGF-23 and parathyroid hormone increases, and hypovitaminosis D. Secreted Klotho protein, formed by extracellular clipping, exerts FGF-23-independent phosphaturic and calcium-conserving effects through its paracrine action on the proximal and distal tubules, respectively. We contend that decreased Klotho expression is the earliest biomarker of CKD and the initiator of CKD-MBD pathophysiology. Maintaining normal phosphate levels with phosphate binders in patients with CKD with declining Klotho expression is expected to reduce mineral and vascular derangements

Klotho and the Aging Process

The klotho gene was originally identified as a putative age-suppressing gene in mice that extends life span when overexpressed. It induces complex phenotypes resembling human premature aging syndromes when disrupted. The gene was named after a Greek goddess Klotho who spun the thread of life. Since then, various functional aspects of the klotho gene have been investigated, leading to the identification of multiple novel endocrine axes that regulate various metabolic processes and an unexpected link between mineral metabolism and aging. The purposes of this review were to overview recent progress on Klotho research and to discuss a novel aging mechanism

Re-evaluation of Clinical Features and Risk Factors of Acute Ischemic Stroke in Japanese Longevity Society

Age is an important factor correlated with stroke prevalence and independently influences stroke outcome especially in Japanese longevity society. To re-evaluate the characteristics of acute ischemic stroke in the old-old, analyses of clinical data on 426 patients registered at a Japanese tertiary emergency hospital were performed under appropriate statistical methods. Clinical features, stroke subtypes, current-known risk factors for stroke, time from onset to arrival, the National Institute of Health Stroke scale (NIHSS) score on admission, length of hospital stay, modified Rankin Scale (mRS) at discharge were compared between two stratified groups by age-at-onset (≧75 and < 75 years old). Significant differences were demonstrated in categories of sex, NIHSS score, length of hospital stay and m-RS. Current-known risk factors for stroke except atrial fibrillation were not prominent in the elderly group. Our study revealed that clinical phenotype and outcome in stroke patients would have been modified and re-evaluation of risk factors is necessary for prevention of ischemic stroke in Japanese longevity society