Research Quiz

  1. Standard Deviation
    • average deviation from the mean in the original
    • unit of measurement. 
  2. Normal distributions
    the mean, mode, and median are the same. Bell-shaped & symmetrical
  3. Positively-skewed
    majority of scores on the lower end of range (the mean  is more positive than mode and median).
  4. Negatively-skewed 
    majority of scoreson the higher end (mean is more negative than mode and median.
  5. Reliability
    consistent,true.  Is a psychometric indicator ofquality of an instrument.  Consistencywhen test is repeated. 
  6. Reliability coefficients
    • can be calculated to provide an indication of
    • the amount of measurement error. 
    • Example: on a 0-1 scale, .8=80% reliability.  Based on the amount of consistency between
    • two sets of scores.
  7. Correlation
    • the statistical technique used to calculate this
    • consistency
  8. Positive correlation
    scores are consistent in the same direction
  9. Negative correlation
    scores are consistent in different directions, so as scores on one test increase, scores on another decrease
  10. Standard Error of Measurement (SEM)
    helpful in interpreting an individual’s score.  Provides an estimation of the range of scores that would be obtained if someone took an instrument over and over again.  Takes reliability into account.
  11. Validity
    • concerns what an instrument measures and how well it does it.  Instruments are not valid, uses of instruments are. 
    • *Reliability is a prerequisite to validity.  If there is too much error, the instrument can’t measure anything consistently.
  12. Convergent evidence
    positive relationship of instrument with other variables with which it should theoretically be related.  *High=if it agrees
  13. Discriminant evidence
    no relationship or negative relationship of instrument with variables from which it should differ in these ways.  *Low=it disagrees. (Happiness/stress/anxiety)
  14. Norm-referenced
    in comparison to others
  15. Norming group
    group who took the instrument to which others’ scores are then compared
  16. Mode
    most frequent score in a distribution
  17. Median
    the score where half the people had a score below it and half had a score above, evenly dividing the scores in half
  18. Mean
    average of the scores
  19. Frequency Distribution
    Can interpret scores more accurately if scores are tallied this way.  (Ex: clas has 30 students, these are their scores....)
  20. Normal curve
    • largest mumber of cases cluster in center (68)
    • Bell-shpaed
  21. Scales of Measurement
    Nominal, Ordinal, Interval, Ratio
  22. Nominal
    • Numbers are used to classify and identify persons
    • Numbers are substituted for names or verbal labels
  23. Ordinal
    Assigns numbers in rank order
  24. Interval
    Helps when interested in differences or intervals between things
  25. Ratio
    • Only scale where you can say "twice as...x"
    • Ratios between the umbers assigned to the person or object
    • Corresponds to the ratios between the attributes measured in these things
    • Addresses issues of relative size, weight, speed, etc. of 2 objects
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