University:
York University
Course:
PSYC 2021 | Statistical Methods I
Academic year:

2024
Views:

304

Pages:

2
Author:

Nick T.

Z-Scores 2-Scores • raw Score a 'regular' score from a dataset; doesn't provide much information doesn't provide any information about the distribution Cannot compare raw scores from different variables in a meaningful way Z-Score specifies location of each X within a distribution Standardized; useful for making comparisons the number of standard deviations a Score is above (+) or below (-) a mean a 2-score of + 1.00 a Score exacty ISD from the mean μ Positive z-score means that you're above the average σ negative z-scare means you're below average μ Mean Standard Deviation - Example Problem I Calculate the z-score from the raw IQ Score of 109 individual Score = 109 mean = 100 - SD = 15 •Z= x-mean/SD -2=109-100/15=.७० Example Problem 2 • Calculate the raw la score from the 2-score 2.5 2-Score 2.50 mean = 100 SD=15 x= (2) (SD) + mean -X=(2.5)(15)+100=137.5 How to Interpret 2-Scores Z-scores • 2-Score of 0: exactly at the mean positive 2-score: above the mean or above average negative 2-Score: below the mean or below average using 2-Scores to make comparisons: "a larger 2-score means you're way above or below average - the sign (-/+) let's you know if you're above or below Standardized Distribution Shape identical to original distribution does not change positions of scores mean always a mean of zero • Standard deviation always a Standard deviation of one numerical value of a 2-score is identical the number of Standard deviations from the mean