Aresearcher designs a study so that his subjects are observed for several weeks with no treatment. they are then given a treatment for several weeks. this is followed by several more weeks in which the treatment is withdrawn. finally, the subjects are given a second round of treatments. the effects of the first treatment, the withdrawal of treatment, and the second treatment are measured. this study is typical of a design.

This is called a Single Case Experimental design.

Single case refers to the participant or cluster of participants under investigation. It is the same participants being investigated in one study. The opposite of this would be an experimental group design in which one group is compared with another. Participants in a single case experimental design research project provide their own control data for the purpose of comparison in a within-subject rather than a between-subjects design.

question - in 1827, john walker, a druggist in a small english town, tipped a splint with sulphur, chlorate of potash, and sulphid of antimony, and rubbed it on sandpaper, and it burst into flame. the druggist had discovered the first friction-chemical match, the kind we use to-day. it is called friction-chemical because it is made by mixing certain chemicals together and rubbing them. although walker's match did not require the bottle of acid, nevertheless it was not a good one. it could be lighted only by hard rubbing, and it sputtered and threw fire in all directions. in a few years, however, phosphorus was substituted on the tip for antimony, and the change worked wonders. the match could now be lighted with very little rubbing, and it was no longer necessary to have sandpaper upon which to rub it. it would ignite when rubbed on any dry surface, and there was no longer any sputtering. this was the phosphorus match, the match with which we are so familiar. according the paragraph what was the benefit of the new phosphorus match? it burst into flame when rubbed on sandpaper. it was made by mixing chemicals. it could be ignited on any dry surface. it threw fire in all directions.

answer - matches required natural chemicals

this is called police cynicism. i hope this .