The Effect of Changing the Length of an Examination on the Index of Internal Consistency
William J. Moonan · The Journal of Experimental Education · 1958
It is the purpose of this paper to examine the ef fect of simultaneous changes in I and r(I) on the value of r(H). The effect on r(H) when the item total score correlations are modified will also be discussed. The formulas to be developed and illustrated in this paper will have most value for the p s y chometrist who is concerned with revising pre liminary forms of an examination. The effe c t s of eliminating items from the tryout form on the internal consistency reliability can be readily es timated if the item-item or item-to tal score cor relations, r(IT), are available.