How can I change the number of Samples in Blender Render in 2.70? I've looked everywhere in the UI, the internet and the manual and can't find it anywhere. This page in the manual makes it look like it should be very obviously found in the Scene tab, but I still don't see it.
That page is for cycles (note the URL:
"Scene settings" in that case refers to settings that effect the entire scene, as opposed to material settings which only affect objects which use that material.
There really isn't a global samples value for BI the way there is for cycles, as the way they work is so different (see How is Cycles different from Blender Internal?). However, BI does use raytracing, similar to cycles, for some things. So where applicable there are sample settings to control the number of raytraced samples:
Global ("scene") settings:
When the Gather method is set to raytrace, you can set the number of samples used for AO and environment lighting in Properties > World > Gather > Sampling:
Per material/lamp settings:
Glossy reflection and refraction in Properties > Materials:
Raytraced shadows on lamps: