Statisical Methods Appendix A.txt

  1. Statistics
    The branch of applied mathematics that researchers use to organize, describe, and draw conclusions about the quantitative results of their studies
  2. Descriptive statistics
    • Statistics used to organize, summarize, and describe data
    • Includes measures of central tendency, variability, and relationships
  3. Measures of central tendency
    • a measure or score that describes the center, or middle, of a distribution or scores
    • Mean � the arithmetic average of a group of scores
    • Median � the middle score or value when scores are arranged from highest to lowest
    • Mode � the score that occurs most frequently in a group of scores
  4. Histogram
    A bar graph that depicts the number of scores within each class interval in a frequency distribution
  5. Variability
    How much the scores in a distribution spread out away from the mean
  6. Range
    The difference between the highest score and the lowest score in a distribution of scores
  7. Standard deviation
    A descriptive statistic reflecting the average amount that scores in a distribution deviate, or vary, from their mean
  8. Normal curve
    • A symmetrical bell-shaped frequency distribution that represents how scores are normally distributed in a population
    • Most scores fall near the mean, and fewer and fewer scores occur in the extremes above or below the mean
    • 68% of scores in a normal distribution fall within 1 standard deviation of the mean (34.13% above and 34.13% below)
    • Almost 95.5% of scores deviations above and
    • 99.72% fall between above and below
  9. The Correlation Coefficient
    A numerical value indicating the strength and direction of a relationship between two variable
  10. Positive correlation
    A relationship between two variable in which both vary in the same direction
  11. Negative correlation
    A relationship between two variable in which an increase in one variable is associated with a decrease in the other variable
  12. Inferential Statistics
    • Statistical procedures based on probabilities that allow researchers to make inferences about the characteristics of the larger population from observations and measurements of a sample
    • Estimates are derived of how much confidence can be placed in those inferences
  13. Population
    The entire group of interest to researchers and to which they wish to generalize their findings; the group from which a sample is selected
  14. Sample
    The portion of any population that is selected for study and from which generalizations are made about the entire population
  15. Tests of statistical significance
    • Statistical tests that estimate the probability that a particular research result could have occurred by chance
    • The estimates derived from tests are stated as probabilities
    • A probability of .05 means that the experimental results would be expected to occur by chance no more than 5 times out of 100
    • The .05 level is usually required as a minimum for researchers to conclude their findings are statistically significant
  16. Replication
    The process of repeating a study with different participants and preferably a different investigator to verify research
Card Set
Statisical Methods Appendix A.txt
Starisical Methods Appendix A