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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. Central Tendencies.
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Statistics Evaluating Data in Research
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
Central Tendencies • A measure of central tendency is a single score that represents a whole set of scores. • Mean – • Average • Mean 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
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
measures of variability STANDARD DEVIATION: how much any 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
The more spread out the scores, the larger the STANDARD 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
Bell CurveA graph of normal distribution 1 SD = 68% of scores 2 SD = 95% of scores 3 SD = 99.7% of scores
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?
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)
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
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
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
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
Ethics in Research • APA Ethical Guidelines • Informed Consent • No harm to patients • Confidentiality • Debriefing
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?