Standardized Testing

Basic Terminology Evaluation: a judgment Measurement: a number Assessment: procedure to gather information

Norm- and Criterion- Referenced Tests Norm- referenced –General ability –Compares people to people –Selecting top candidates Criterion- referenced –Mastery –Basic skills –Prerequisites –Grouping for instruction

What Do Test Scores Mean? Standardized test Norming sample Frequency distributions Central tendency Variability

Frequency Distribution Histogram

Central Tendency Mean –The arithmetic average Median –The middle score Mode –The most frequently occurring score

Variability Range Standard deviation –Indicates how much the scores vary from the mean

Calculating the Standard Deviation Calculate the mean:  Subtract the mean from each score:  Square each difference:   Add all the squared differences:   Divide by the number of scores:   N Find the square root :   N

Sample Problems

Calculate the mean, median, mode, range, and standard deviation for the following sets of scores Reading –95 –90 –85 –80 –75 –70 –65 –60 –55 Arithmetic –76 –78 –77 –71 –75 –79 –74 –72 –73

Calculations Reading   – – – – – – – – –    Arithmetic   – – – – – – – – –   

=12.91 Calculations continued Reading          Arithmetic        Standard deviations

Completed Calculations Reading –Mean = 75 –Mode = none –Median = 75 –Range = 40 –Standard deviation = Arithmetic –Mean = 75 –Mode = none –Median = 75 –Range = 8 –Standard deviation = 2.58

Normal Distributions The “bell curve” Mean, median, mode all at the center of the curve 50% of scores above the mean 50% of scores below the mean

Normal Distribution with Standard Deviations 2% 34% 14% 0 +1SD-1SD-2SD+2SD-3SD+3SD Percent of the population Standard Deviation Units

Types of Scores Percentile rank Grade-equivalent Standard scores –z scores –T scores –Stanine scores

Interpreting Test Scores Reliability True score Standard error Confidence intervals Validity

Types of Standardized Tests Achievement Tests –Measure previous learning Diagnostic Tests –Identify strengths and weaknesses Aptitude Tests –Measure abilities

Issues in Testing Widespread testing Accountability and high stakes testing