PSY 420 Chapter 5 Book Notes
PSY 420 Chapter 5 Book Notes PSY420
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This 2 page Class Notes was uploaded by Samantha Bishop on Sunday September 18, 2016. The Class Notes belongs to PSY420 at Lenoir-Rhyne University taught by Dr. Gordon Cappelletty in Fall 2016. Since its upload, it has received 4 views. For similar materials see Psychological Assessment in Psychology at Lenoir-Rhyne University.
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Date Created: 09/18/16
PSY 420 Chapter Five Book Notes Chapter 5: How Do Test Users Interpret Test Scores? (p.109148) Levels of Measurement p.110116 Level of measurement: the relationship among the numbers we have assigned to the information Critical to describing and interpreting psychological test and measurement results because we use numbers, at the test or survey item level, the scale level, and the test result level. Four Levels of Measurement: 1. Nominal numbers are assigned to represent labels or categories of data only (frequency, mode, chisquare) 2. Ordinal numbers are assigned to rankorder data (frequency, mode, median, percentile, rankorder correlation) 3. Interval numbers are assigned to rankorder data and the distance between numbers is judged to be equal (frequency, mean, mode, median, standard deviation, Pearson productmoment correlation, t test, F test) 4. Ratio numbers are assigned to rankorder data and the distance between numbers is judged to be equal and there is an absolute zero point (frequency, mean, mode, median, standard deviation, Pearson productmoment correlation, proportion, t test, F test) *descriptive chart on p.113* Procedures for Interpreting Test Scores p.117134 Raw scores most basic calculated scores from a psychological test Norm group a previously tested group of individuals Frequency distributions an orderly arrangement of a group of numbers and show the actual number or percentage of observations that fall into that range or category Class intervals a way to group raw scores so as to display them (should aim for approximately 15 groups of scores according to Lyman, 1998) Histogram a bar graph used to represent frequency data in statistics (picture on p.121) Normal probability distributions (normal curves) theoretical distributions that exist in our imagination as perfect and symmetrical in a bell shape (picture on p.122) Descriptive statistics describe data using measures of central tendency Measures of central tendency value that helps us understand the middle of a distribution or set of scores (mean, median, mode) Mean average score Median middle score in a group of scores Mode most common score in a distribution Outliers a few values that are significantly higher or lower than most of the scores Measures of variability describes a set of scores in numerical form Range highest score minus the lowest score Variance tells us whether individual scores differ substantially or are similar from the mean Standard deviation most commonly used measure of variability (square root of variance) Measures of relationship must have at least two sets or distributions of scores from the same individuals Correlation coefficient describes the relationship Pearson productmoment correlation coefficient measures linear associations between 2 variables that have been measured on interval or ration scales Standard Scores p.134139 Standard scores universally understood units in testing that allow test users to evaluate a person’s performance Linear transformations change the unit of measurement but do not change the characteristics of the raw data Percentages divide raw score by total possible score Standard deviation units refer to how many standard deviations an individual score falls away from the mean Z score represented as a whole number with a decimal point T score always have a mean of 50 and a standard deviation of 10 and are always positive Area transformations change the unit of measurement and the unit of reference Percentiles percentage of scores in a distribution that fall at or below a given raw score Stanines a standard score scale with nine points that allows us to describe a distribution in words instead of numbers (graph on p.139) The Role of Norms p.139145 Norms test scores achieved by some identified group of individuals Normbased interpretation process of comparing a individual’s test score to a norm group Age norms/grade norms common types of norms that help determine what age or grade level an individual is performing at Percentile rank ranks individuals on a scale of 1% to 100%
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