# Psychometrics

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1. What are the 4 Scale of Measurement?
Nominal, Ordinal, Interval, Ratio
2. Nominal Scale of Measurement
Classify, No logical order
3. Ordinal Scale of Measurement
Classify and rank or order
4. Interval Scale of Measurement
Classify, orders, adds zero (arbitrary) and equal units
5. Ratio Scales of Measurement
Classify, order, equal units, true zero point

True Ratio
6. Why not use raw scores?
Lack of comparability, original score of 30 could mean several things, need to change it into something with a meaningful value such as a derived score
7. Examples of Derived Scores
Age/Grade equivalents, perventile ranks, standard scores
8. Name two types of Developmental Scores
Age Equivalent Scores

9. What are some problems with age and grade scores?
Different Meaning:Raw scores can mean several different things

Misenterpretation

Meaningful Difference: Most tests don't have enough items at a specific age grade level

Ordinal Scale: Can't get standard error of measurement

Imply constant rate of growth: unequal intervals

Imply false standard

Different meanings across tests
10. What are Percentiles?
Not percentage correct, as high or higher than xx% of children on this test (not as well or better), among easiest to interpret for parents, not useful for comparing scores (overestimate differences in center of normal curve and underestimate differences on tails)
11. Why are percentiles not useful in comparing scores?
They overestimate differences in the center of the normal curve and underestimate difference on the tails of the normal curve
12. What are standard scores?
They make use of means and standard deviations, derived from z-scores, best scores for comparing
13. What are z-scores? What is the formula?
Z-scores are the number of SD's from the mean, easy to convert from z-scores to others

Z scores = (Raw-Mean)/Standard Deviation
14. T-Scores
• Mean = 50
• Standard Deviation = 10
15. What are norm referenced tests?
Tests that compare score to a normative sampe, must control variables that are likely to affect variable meausuring.
16. What is a normative sample?
A representative sample that matches the population. Larger size means more stability. Relevance of Comparisons.
17. M=
Mean
18. SD=
Standard Deviation
19. SEM=
SEM=Standard Error of Meausrement
20. Central Tendency
Mean, some include mode and median
21. Variation (Scatter)
Standard Deviation, Variance, some include Range
22. Name the four types of notation.
Central Tendency, Variation (Scatter), Standard Error of Measurement, Correlation =r
23. Name ways to summarize data for a single variable.
Charts, graphs (histograms), central tendency, variabiltiy
24. What is a histogram? Name its different parts.
Histogram (history of data) = Bar Graph

• Vertical Bars=data, frequency
• Baseline (horizontal axis)=observed scores on the dependent variable
25. What is a frequency polygon? Name its parts.
Frequency Polygon = Line Graph

Vertical lines = score intervals, individual scores

Baseline (horizontal axis) = frequencies or percentages
26. Skew
Positive scew: has a longer tail on the higher scores or right side

Negative scew: has a longer tail on the lower scores or left side
27. Kurtosis
Playukurtic Curve (very low and wide)

Leptokutic Curve (very high and narrow)
28. What is a tendency
A data trend
29. Name two types of trends.
Measures of central Tendency, Measures of dispersion (spread or variability)
30. What are types of central tendency measures?
Median Mean Mode
31. What are measures of dispersion?
Measures of variability = range, variance, and standard deviation
32. What is mode?
The number that appears most often
33. What is the median? And how do you calculate it?
The middle score, 1/2 below and 1/2 above, put data in order and find the middle one, if you have an even number you add the middle two numbers and divide by two
34. How do you find the mean?
Add up all of the scores and divide by the number of scores
35. Differences in Distributions:
Where are the median, mode, and mean in:
a symmetrical distribution?
a positively skewed distribution?
a negatively skewed distribution?
Symmetrical Distribution: All line up in the middle

Positive Skew (Left to right): Mode, Median, Mean

Negative Skew (Left to right): Mean, Median, Mode
36. Measures of Variability
how spread out the scores are, measures of variability cannot be negative, suggests dispersion
37. What are Homogeneous Scores?
Little variability
38. What are heterogeneous scores?
High Variability
39. What is range?
the difference between the lowest and the highest
40. What is interquartile range?
Spread among middle 50% of scores
41. Name the measures of variability.
Range, Interquartile Range, Variance, Standard Deviation
42. What is variance? How do you calculate it?
Variance is how much scores deviate from the mean (used more in statistics and less in measurement), average of the squared deviation scores
43. What is Standard Deviation? How do you Calculate it?
• SD is another measure of dispersion
• SD=square root of variance
• SD puts scores back in original metric
• Useful for describing scores, inherent in any type of standard scores,
44. What is a normal curve?
A normal curve is a unimodal, symmetrical graphic depiction of scores
45. How do you summarize data on more than one variable?
Bivariate relations, correlations
46. What is a correlation?
 Author: Anonymous ID: 108830 Card Set: Psychometrics Updated: 2011-10-14 02:49:34 Tags: statistics vocab Folders: Description: For my psychometrics Quiz Show Answers: