Each engineering apprentice entering a certain large firm is given a written test on his basic technical knowledge, his work being graded A, B, C, or D (in descending order of merit). At the end of his third year with the firm his section head gives him a rating based on his current performance; the four possible classifications being 'excellent', 'very good', 'average', and 'needs to improve'. The results for 492 apprentices are given in the following two-way table. Analyse the data, and state clearly what conclusions you draw regarding the usefulness, or otherwise, of the written test as an indicator of an entrant's subsequent performance in the firm. Written test result Section head's assessment Excellent Very good Average Needs to improve 42377 A B 26 33 22 29 43 71 1232 C D 21 35 72 12 11 =249 11 20 45 (Manch. Dip.)