Hays, Cha 6: Understanding and Transforming Raw Scores Flashcards
Raw scores are:
Practically meaningless on standardized tests
- Only one at hand that uses is Miller Analogies Test
What are Measures of Central Tendency?
When scores are distributed, the most commonly measured score
How is central tendency measured?
Mean, median, mode
What is variability?
How much scores spread out around the mean
What is variability measured?
Range (largest-smallest score) Standard Deviation (most commonly used)
What is a standard score?
What the raw score is turned into
Describe the characteristics of a normal curve.
- Shaped like a bell, symmetrical (Ex. Intelligence (normally distributed)
- ~34% of scores will lie 1 SD above the mean and another ~34% will lie 1 SD below the mean
- ~14% will lie b/w 1 and 2 SD above mean, and another ~14% will lie b/w 1 and 2 SD below mean
- ~2% will lie b/w 2 and 3 SD above mean, and another ~2% will lie b/w 203 SD below the mean
What is the mean?
The middle of bell curve
- Most mean score on IQ tests is 100; cannot cap out (we don’t know how high score can go - Hawkings, Michealangelo - or how low score can go)
- Easiest quality to talk about that is normally distributed (Intelligence)
What is skewness?
Distributions that do not look normally distributed (the bell is curved more to the left or to the right, rather than symmetrical)
What is a norm?
The group the instrument was designed on
- Most standardized instruments are norm referenced; scores from your client can be compared back to the original statistics of the norm group
What is a grade-equivalent score?
Used in education to see where the child is at in school - raw score turned into a grade equivalent
- Most misinterpreted score, people automatically assume it means their kid is at that specific level
- It means that their child took a test and did about the same as a student in the grade equivalent score would get if they took the same test
What is an age-equivalent score?
Used in education to see where the child is at in school with children around their age. Misleading as well.
What is a rank score?
Where scores are listed in order of rank (simplest)
What is a percentile rank score?
Scores tell client how many people they scored better than on that test admin. “If a person has a percentile score of 85, that means 85% of people scored lower than that person” don’t ever turn it around
- National Percentile Rank: Same but compared nationally
- Raw scores converted to percentiles end up at the ends of the distribution
What is a problem with the percentile rank score?
Dramatic difference b/w scores that change on the ends of distribution than scores that are towards the middle of distribution
- There are less scores to compete with at the ends, so change is more noticeable
What is a standard score?
Raw score, converted to a score that tell you how far the raw score is from the mean in standard deviation units.
What are two types of standard scores?
Z Score and T Score
What is a Z Score?
Changes mean to 0 and SD to 1
- Scores given in SD “score fell 1.5 SD above mean”
What is a T Score?
Common on standardized tests; Raw score converted to T score has mean of 50 and SD of 10
- Scores given in SD
What is the mean and SD of the SAT?
m500, SD100
What is the mean and SD of the ACT?
m15, SD5
What is an IQ score?
Intelligence Quotient (not a quotient anymore, it’s a standard score). Tells you how far your score deviated in SD from other people your age. - People are starting to equate IQ score with innate intelligence; which is not true, IQ scores can change
What is the prior ratio IQ?
mental age:chronological age
What is the mean and SD of the Stanford-Binet Intelligence Test?
M100, SD15 or 16
What is the Standard Error of Measurement (SEM)?
When you take a test of almost every kind, every test has a standard error for the score that has been calculated (differs for every test)
What is a confidence interval?
Take score obtained and you can say with some degree of certainty that the administration of this instrument, this person made this score + or - the standard error
- This is how you establish a reliability estimate for any individual score (it’s the SEM)
When looking at scores, the ones in the _____ are always the most reliable b/c they’re least apt to change. The ones at the _____ are apt to change the most when giving the same test to the same person
middle; ends
Do not confuse percentiles with _____
Percentages
