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Shahjahan Khan

Publications and source records attributed to Shahjahan Khan.

3 recordsLinked to original sources

Bi-Directional Grid Constrained Stochastic Processes' Link to Multi-Skew Brownian Motion

Bi-Directional Grid Constrained (BGC) stochastic processes (BGCSPs) constrain the random movement toward the origin steadily more and more, the further they deviate from the origin, rather than all at once imposing reflective barriers, as does the well-established theory of It^o diffusions with such reflective barriers. We identify that BGCSPs are a variant rather than a special case of the multi-skew Brownian motion (M-SBM). This is because they have their own complexities, such as the barriers being hidden (not known in advance) and not necessarily constant over time. We provide an M-SBM theoretical framework and also a simulation framework to elaborate deeper properties of BGCSPs. The simulation framework is then applied by generating numerous simulations of the constrained paths and the results are analysed. BGCSPs have applications in finance and indeed many other fields requiring graduated constraining, from both above and below the initial position.

math.PR

Hidden Geometry of Bi-Directional Grid Constrained Stochastic Processes

Bi-Directional Grid Constrained (BGC) stochastic processes (BGCSP) are constrained Itô diffusions with the property that the further they drift away from the origin, the more resistance to movement in that direction they undergo. We investigate the underlying characteristics of the BGC parameter $Ψ(x, t)$ by examining its geometric properties. The most appropriate convex form for $Ψ$, i.e. the parabolic cylinder is identified after extensive simulation of various possible forms. The formula for the resulting hidden reflective barrier(s) is determined by comparing it with the simpler Ornstein-Uhlenbeck process (OUP). Applications of BGCSP arise when a series of semipermeable barriers are present, such as regulating interest rates and chemical reactions under concentration gradients, which gives rise to two hidden reflective barriers.

math.PR

Increasing power of the test through pre-test - a robust method

This paper develops robust test procedures for testing the intercept of a simple regression model when it is \textit{apriori} suspected that the slope has a specified value. Defining unrestricted test (UT), restricted test (RT) and pre-test test (PTT) corresponding to the unrestricted (UE), restricted (RE), and preliminary test estimators (PTE) in the estimation case, the M-estimation methodology is used to formulate the M-tests and derive their asymptotic power functions. Analytical and graphical comparisons of the three tests are obtained by studying the power functions with respect to size and power of the tests. It is shown that PTT achieves a reasonable dominance over the others asymptotically.

math.ST