PSYCH 100A Lecture Notes - Lecture 5: Raw Score, Inflection Point, Percentile Rank
Document Summary
Variable values must be in descending order. Range method: highest value minus lowest value divide by 2. Median: order values then find the middle number. Mode is larger than the mean distribution is negatively skewed. Only uses two points in the entire set of data. Gives us units of measurements that make sense. Deviation score: variable value minus the mean. In order to get an average deviation that is not 0, we need to square all the deviations scores to get positive values. Sample sd/variance is adjusted so that the denominator is n-1 not n. Find the number of scores equal to or below the score then divide by the total number of observations. A change in one point can lead to a significant change in percentile in one area of the distribution and a less significant change in another area of the distribution. Raw score difference is same but as you move up the distribution the percentile difference changes.
