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CATALYST: 2 TRUTHS AND A LIE! Write down 3 statements about yourself…two truths…and one lie. We’ll try to guess which one is the lie!. Discuss uncertainty in science Describe statistical measures we can use to address uncertainty in our findings. Today:. Fun with Puzzles!.
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CATALYST:2 TRUTHS AND A LIE!Write down 3 statements about yourself…two truths…and one lie.We’ll try to guess which one is the lie!
Discuss uncertainty in science • Describe statistical measures we can use to address uncertainty in our findings Today:
What are some ways this activity was similar to trying to answer a scientific question?
ARE MY FINDINGS TRUE? ARE MY FINDINGS SIGNIFICANT?
TOXIC SLUDGE! Mexican Walking Fish Dead Mexican Walking Fish Is it TRUE that toxic sludge kills the mexican walking fish? Becomes… Is there a SIGNIFICANT DIFFERENCE in the life expectancy of m.w.f exposed to the toxic sludge and unexposed m.w.f?
TOXIC SLUDGE! Mexican Walking Fish Dead Mexican Walking Fish Accepted level of uncertainty in science = 5% = p We need to be 95% confident that are findings are NOT due to random chance!
WHAT DO WE MEAN BY RANDOM CHANCE? TOXIC SLUDGE! Mexican Walking Fish Dead Mexican Walking Fish
How do we address uncertainty in our lab reports? • Whenever we report measures of central tendency we also report measures of dispersion • 95% Confidence Interval • Calculating p! • Chi-square • Student’s t-test
Measures of Dispersion RANGE!
Which of these sets of data has a larger range? 5 6 8 2 9 5 5 0 28 7 5 40
Measures of Dispersion STANDARD DEVIATION s = ∑ (xi – x)2 n - 1
Which of these sets of data has a smaller standard deviation? 5 6 8 2 9 5 5 0 28 7 5 40
Which of these sets of data has a larger standard deviation?
Which of these means is more certain? Mean Life Expectancy = 15 months (s = 2) Mean Life Expectancy = 15 months (s = 7)
Practice Calculating Mean + StDev 5 6 8 2 9 5 5 0 28 7 5 40
Standard Error SEX = s n
Practice Calculating Standard Error 5 6 8 2 9 5 5 0 28 7 5 40
95% Confidence Interval 95% CI = SE x tp(n-1)
Critical Values of the Student’s T Distribution
Practice Calculating 95% CI 5 0 28 7 5 40 5 6 8 2 9 5
TIME TO PRACTICE!
The Nature of Science Analogy Assignment due Tuesday! • Parent / Student Contract • Student Survey • Lab Safety Contract • Email Homework