PSY300 Lecture Notes - John Tukey, Central Tendency, Parametric Statistics
Document Summary
Ratio and interval scale parametric data. This distinction determines the types of statistical analyses that may be applied to the data. A z score is the number of standard deviations a score is above or below the mean. Formula to change a raw score to a z score: z = (x-m)/sd. Formula to change a z score to a raw score: x = (z) (sd) + m. If you get 8/10 on a wordsum, and it was normally distributed, what top % of the distribution would you occupy? . If we wanted to contact at risk individuals, defined as the lowest 2% (z < -2), what wordsum score would we use as a cutoff to recognise such individuals? . Shape: t-distribution with df based on two samples: dftotal = df1 + df2. Observed t-score for the difference between the two actual means: t = (m1 m2)/sdifference.
