How to Design and Evaluate Research in Education

A z-table gives percent of scores from any score to the mean (Appendix, pp. A-4/5) The probability for getting higher or lower than any given score can then be calculated. T-scores are often used because negative z scores awkward (all T-scores are positive) Multiply z times 10, then add 50 (p. 212 Table 10.15) ................
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