non graduated interpolation (beginner)

Discussion created by Masare2 on Apr 19, 2012
I'm not very skilled in geostatistical analysis, and up to now I have always found the informations I needed on this forum but..
The question is small, but I will explain all the situation so maybe you can help me better!
(I have the geostatistical analyst tool)
my map is divided in 3 areas, in each area I have points and lines that contain a value that I need to analyze
the analysis must be separated for the three areas, so I created three different shapefiles containing the lines (and 3 for the points) and probably I'll have to create 3 shapes for the 3 areas
my values are discontinuous (1.7 1.8 2.0 2.3 etc)
the question is (finally!): what is the best interpolation method if I want it to be exact (under my line I need exactly my value) and not graduated? I mean if there is no 1.9 value, I don't want a 1.9 interpolated zone... I just need to divide my areas between the given values!

another can I use values coming both from a linear shapefile and a punctual shape? I better transform lines in a singol central point?