Johnston, S.J.Jordaan, Kerstin HeidrunJooste, Alta2015-11-162016S.J. Johnston, A. Jooste & K. Jordaan (2016) Quasi-orthogonality of some hypergeometric polynomials, Integral Transforms and Special Functions, 27:2, 111-125, DOI: 10.1080/10652469.2015.1098635.1065-2469 (print)1476-8291 (online)10.1080/10652469.2015.1098635http://hdl.handle.net/2263/50490The zeros of quasi-orthogonal polynomials play a key role in applications in areas such as interpolation theory, Gauss-type quadrature formulas, rational approximation and electrostatics. We extend previous results on the quasi-orthogonality of Jacobi polynomials and discuss the quasi-orthogonality of Meixner–Pollaczek, Hahn, Dual- Hahn and Continuous Dual-Hahn polynomials using a characterization of quasi-orthogonality due to Shohat. Of particular interest are the Meixner–Pollaczek polynomials whose linear combinations only exhibit quasi-orthogonality of even order. In some cases, we also investigate the location of the zeros of these polynomials for quasiorthogonality of order 1 and 2 with respect to the end points of the interval of orthogonality, as well as with respect to the zeros of different polynomials in the same orthogonal sequence.en© 2015 Taylor and Francis. This is an electronic version of an article published in Integral Transforms and Special Functions, vol. 27, no. 2, pp. 111-125, 2016. doi : 10.1080/10652469.2015.1098635. Integral Transforms and Special Functions is available online at : http://www.tandfonline.comloi/gitr20.Hypergeometric polynomialsQuasi-orthogonal polynomialsZerospFq polynomialsPostprint Article