This paper reviews the recent developments in the field of the variance-ratio tests of random walk and martingale hypothesis. In particular, we present the conventional individual and multiple VR tests as well as their improved modifications based on powertransformed statistics, rank and sign tests, subsampling and bootstrap methods, among others. We also re-examine the weak-form efficiency for...

This paper identi®es four categories of formal stock market in Africa: South Africa, medium-sized markets, small new markets which have experienced rapid growth, and small new markets which have yet to take o€ . The hypothesis that a stock market price index follows a random walk is tested for South Africa, ®ve medium-sized markets (Egypt, Kenya, Morocco, Nigeria and Zimbabwe) and two small new...

In this paper we have proposed some ratio-type estimators of finite population variance using known values of parameters related to an auxiliary variable such as quartiles with their properties in simple random sampling. The suggested estimators have been compared with the usual unbiased and ratio estimators and the estimators due to [2], [12, 13, 14] and [3]. An empirical study is also carried...

Scholars frequently use ex post evaluation metrics such as the Mean Absolute Percentage Error (MAPE) to estimate forecast accuracy. However, ante are essential know whether a given forecasting model is suitable for variable irrespective of outcome evaluations. The measures help us ensure that accurate, not by chance. current study presents Posterior Variance Test (PVT), which can serve an measu...