PSYC32H3 Chapter Notes - Chapter 1: Percentile Rank, Truncated Distribution, Standard Score
Document Summary
Basis of many commonly used statistical and psychometric models and is the assumed distribution for many psychological variables. The ordinate (height of the curve at any point along the x-axis) is the proportion of persons within the sample who obtained a given score. Normal curve can also be referred to as a probability distribution. Percentile: the percentage of scores that fall at or below a given test score. Converting scores to percentiles raw scores are standardized". Usually to z scores z = (x x)/sd x= measurement value (test score) X= the mean of the test score distribution. Sd= the standard deviation of the test score distribution. Resulting distribution of z scores has a mean of 0 and a sd of 1. Linear transformations of z scores: t scores and other standard scores. Linear transformation can be used to produce other standardized scores. T scores, z scores, standard scores, and percentile equivalents are derived from samples.
