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Statistics

Statistics. Evaluating Data in Research. Percentile Ranks. Joey finished at the 74 th percentile on his EOC Algebra test. 74 th percentile means Above 74% of test takers Actual #75, there is no 100 th percentile. How do we interpret our data?. We look for……. Central Tendencies.

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Statistics

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  1. Statistics Evaluating Data in Research

  2. Percentile Ranks Joey finished at the 74th percentile on his EOC Algebra test. • 74th percentile means • Above 74% of test takers • Actual #75, there is no 100th percentile

  3. How do we interpret our data? • We look for……..

  4. Central Tendencies • A measure of central tendency is a single score that represents a whole set of scores. • Mean – • Average • most easily skewed by outliers (extreme numbers) • Median • Middle value (midpoint, or 50th percentile) • (Place in sequential order and find middle number) • Mode • Most frequently occurring score

  5. Statistical Reasoning A Skewed Distribution 15 20 25 30 35 40 45 50 90 475 710 70 Mode Median Mean One Family Income per family in thousands of dollars

  6. Measures of variability RANGE: difference between the highest and lowest scores (can be deceptive due to outliers) MEAN 7 6 5 4 3 2 1 1 11 1 2 3 4 5 6 7 8 9 10 11 12

  7. measures of variability STANDARD DEVIATION: how much any given score differs from the average, or mean score MEAN +1 sd -1 sd 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 10 11 12

  8. The more spread out the scores, the larger theSTANDARD DEVIATION. MEAN +1 sd -1 sd 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 10 11 12

  9. Bell CurveA graph of normal distribution 1 SD = 68% of scores 2 SD = 95% of scores 3 SD = 99.7% of scores

  10. Weighing the odds… • Player B – team will know where to run • 2 High School punters • Kicker A: • mean distance: 39.8 yds • Standard deviation: + 14 yds. • Kicker B: • mean distance: 34.5 yds. • Standard deviation: + 4 yds. • Which player do you play?

  11. Standard Deviation • Z score • number that represents how many SD’s a particular score differs from the mean • The mean score for the class was 80, with a SD of 10. • Joey scored 60 on his test. What’s his z score? • Betsy scored a 95. what is her z score?

  12. Statistical Significance When is a study’s data significant? When there is a significant difference between the results (data) for the control group and experimental group. When the data is reliable (consistent)

  13. Statistical Practice… • 1. What is the mean of the following distribution of scores: 2, 3, 7, 6, 1, 4, 9, 5, 8, 2? A. 5 B. 4 C. 4.7 D. 3.7 E. 6 Answer: c

  14. Statistical Practice… • What is the median of the following distribution of scores: 1, 3, 7, 7, 2, 8, 4? a. 1 b. 2 c. 3 d. 4 Answer: d

  15. Statistical Practice… • What is the mode of the following distribution: 8, 2, 1, 1, 3, 7, 6, 2, 0, 2? a. 1 b. 2 c. 3 d. 7 Answer: b

  16. One for the record… • Seven members of a Girl Scout troop report the following individual earnings from their sale of candy: $4, $1, $7, $6, $8, $2, and $7. In this distribution of individual earnings: • The mean is equal to the mode and equal to the median • The mean is less than the mode and equal to the median • The mean is equal to the mode and greater than the median • The mean is greater than the mode and greater than the median • The mean is less than the mode and less than the median Mean=5, median=6, mode=7 Answer=e

  17. Ethics in Research • APA Ethical Guidelines • Informed Consent • No harm to patients • Confidentiality • Debriefing

  18. Animal Testing • Statistics to consider… • 30,000,000 animals used for research each year constitutes 1% of animals killed each year to eat. • 200,000 dogs and cats researched annually / animal shelters euthanize 50x that each year Is it morally acceptable to place the well- being of humans above other animals regarding research?

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