The concept of two-phase sampling was first given by Neyman (1938),
later on several simple and general regression and ratio estimators have
been suggested, starting from Mohanty (1967), Srivastava (1970), Chand
(1975), Kiregyera (1980, 84), Mukerjee et al. (1987), Srivastava et
al.(1990), Roy (2003)and Samiuddin and Hanif (2006,07). Use of
multi-auxiliary information for ratio and regression estimators, were
considered, by Olkin (1958), Goswami and Sukhatme (1965), Raj (1965),
Rao and Mudholkar (1967), Tripathi (1970, 1976), Tripathi and Ahmed
(1995), Sen (1972), Tripathi (1987), Singh and Namjoshi (1988), Tripathi
and Khattree (1989), Tripahi and Chaubey (1993), Ahmed (2003), Martin
and Steven (2004) and Ahmad at el. (2008). In this monograph we have
provided general classes of regression and ratio estimators for
two-phase and multi-phase sampling using multi-auxiliary variables for
estimating single as well as multiple variables of interest.The
theoretical developments provided in this monograph can be useful in
multipurpose surveys in which the problem is to estimate population
means of several variables simultaneously in the field like
agricultural, forestry etc.