PSYCH ASSESSMENT

• Reliability


  • Basic Research = 0.70 to 0.90
  • Clinical Setting = 0.90 to 0.95
• Item Difficulty


  • The optimal boundary lines for the "upper" and "lower" areas of distribution of scores will demarcate the upper and lower 27% of distribution of scores if normal, 33% if platykurtic
  • 0.27/n, wherein n = no. of students
• Interrater Reliability Coefficient


  0 means 0% of the variance in the scores assigned by the scorers was attributed to true differences and 100% to error
• 1. Value


  • P-Value ≤ ∞, reject null hypothesis
  • P-Value ≥ ∞, accept null hypothesis
• Mean


  • The average of all the raw scores
  • Equal to the sum of the observations divided by the number of observations
  • Interval and ratio data (when normal distribution)
  • Point of least squares
  • Balance point for the distribution
  • Susceptible to outliers
• Median


  • The middle score of the distribution
  • Ordinal, Interval, Ratio
  • For extreme scores, use median
  • Identical for sample and population
  • Also used when there has an unknown or undetermined score
  • Used in "open-ended" categories (e.g., 5 or more, more than 8, at least 10)
  • For ordinal data
  • If the distribution is skewed for ratio/interval data, use median
• Mode


  • Most frequently occurring score in the distribution
  • Bimodal Distribution: if there are two scores that occur with highest frequency
  • Not commonly used
  • Useful in analyses of qualitative or verbal nature
  • For nominal scales, discrete variables
  • Value of the mode gives an indication of the shape of the distribution as well as a measure of central tendency
• Range


  • Equal to the difference between highest and the lowest score
  • Provides a quick but gross description of the spread of scores
  • When its value is based on extreme scores of the distribution, the resulting description of variation may be understated or overstated
• Interquartile Range


  Difference between Q1 and Q2
• Semi-Quartile Range


  Interquartile range divided by 2
• Standard Deviation


  • Approximation of the average deviation around the mean
  • Gives detail of how much above or below a score to the mean
  • Equal to the square root of the average squared deviations about the mean
  • Equal to the square root of the variance
  • Distance from the mean
• Variance


  • Equal to the arithmetic mean of the squares of the differences between the scores in a distribution and their mean
  • Average squared deviation around the mean
• Percentile or Percentile Rank

  • Not linearly transformable, converged at the middle and the outer ends show large interval
  • Expressed in terms of the percentage of persons in the standardization sample who fall below a given score
  • Indicates the individual's relative position in the standardization sample
  • Essential in creating normalized standardized scores
• Quartile


  • Dividing points between the four quarters in the distribution
  • Specific point
  • Quarter: refers to an interval
• Decile/STEN


  • Divide into 10 equal parts
  • A measure of the asymmetry of the probability distribution of a real-valued random about its mean
• Pearson R


  Interval/ratio + interval/ratio
• Spearman Rho


  Ordinal + ordinal
• Biserial


  Artificial Dichotomous + interval/ratio
• Point Biserial


  True dichotomous + interval/ratio
• Phi Coefficient


  Nominal (true dic) + nominal (true/artificial dic.)
• Tetrachoric


  Art. Dichotomous + Art. Dichotomous
• Kendall's


  3 or more ordinal/rank
• Rank Biserial


  Nominal + ordinal
• 1. test Independent (Unpaired T-test)

  Two separate groups, random assignment
• 1. Test Dependent (Paired T-test)


  One group, two scores
• One-Way ANOVA


  3 or more groups, tested once
• One-Way Repeated Measures


  1 group, measured at least 3 times
• Two-Way ANOVA


  3 or more groups, tested for 2 variables
• ANCOVA


  Used when you need to control for an additional variable which may be influencing the relationship between your independent and dependent variable
• ANOVA Mixed Design


  2 or more groups, measured more than 3 times
• MANOVA


  Used to test the differences between the means of multiple dependent variables across two or more independent groups
• Mann Whitney U Test


  1. test independent
• Wilcoxon Signed Rank Test


  1. test dependent
• Kruskal-Wallis H Test


  One-way/two-way ANOVA
• Friedman Test


  ANOVA repeated measures
• Lambda


  For 2 groups of nominal data
• Chi-Square Goodness of Fit


  Used to measure differences and involves nominal data and only one variable with 2 or more categories
• Test of Independence


  Used to measure correlation and involves nominal data and two variables with two or more categories
• Linear Regression of Y on X


  • Y = a + bX
  • Used to predict the unknown value of variable Y when value of variable X is known
• Linear Regression of X on Y


  • X = c + dY
  • Used to predict the unknown value of variable X using the known variable Y