Rationing in the United Kingdom meat, tea, jam, biscuits, breakfast cereals, cheese, eggs, lard, milk, and canned and dried fruit. In June 1942 the Combined Food Board was set up by Great Britain and the United States to coordinate the world supply of food to the Allies, with special attention to flows from the U.S. and Canada to Britain. Almost all foods apart from vegetables and bread were rationed by August 1942. Strict rationing inevitably created a black market. Almost all controlled items were rationed by weight but meat was rationed by price. Fresh vegetables and fruit were not rationed but supplies were limited. Some
Item response theory they contribute greatly but over a narrow range. Less discriminating items provide less information but over a wider range. Plots of item information can be used to see how much information an item contributes and to what portion of the scale score range. Because of local independence, item information functions are additive. Thus, the test information function is simply the sum of the information functions of the items on the exam. Using this property with a large item bank, test information functions can be shaped to control measurement error very precisely. Characterizing the accuracy of test scores is perhaps the