Do you mean a<strong> shear wall, a wall in a building or a retaining wall?
There are numerous other factors which might be considered, such as the material from which the wall is constructed, the use of a building code and whether you are attempting a computer analysis or a hand one.
The following web link, for example, indicates that if you are trying to design a shear wall to BS 8100 (the UK code for concrete design) and use finite element analysis, you could assume that the distribution of forces in the wall is equal:
http://www.cscworld.com/downloads/IStructE_Journal_-_Shear_Wall_Modelling.pdf
Stone Masonry | Shear Walls