Sec1-3 - STAT 101 Dr Kari Lock Morgan Collecting Data...

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12/23/2012 1 Statistics: Unlocking the Power of Data Lock 5 STAT 101 Dr. Kari Lock Morgan 9/4/12 Collecting Data: Experiments SECTION 1.3 Association versus Causation Confounding Variables Observational Studies vs Experiments Randomized Experiments Statistics: Unlocking the Power of Data Lock 5 - use-causes-mental-deficit Statistics: Unlocking the Power of Data Lock 5 Statistics: Unlocking the Power of Data Lock 5 DATA Data Collection and Bias Population Sample TODAY Statistics: Unlocking the Power of Data Lock 5 Explanatory and Response If we are using one variable to help us understand or predict values of another variable, we call the former the explanatory variable and the latter the response variable Examples: Does meditation help reduce stress? Does sugar consumption increase hyperactivity? Statistics: Unlocking the Power of Data Lock 5 Association and Causation Two variables are associated if values of one variable tend to be related to values of the other variable Two variables are causally associated if changing the value of the explanatory variable influences the value of the response variable
12/23/2012 2 Statistics: Unlocking the Power of Data Lock 5 Explanatory, Response, Causation For each of the following headlines: Identify the explanatory and response variables (if appropriate). Does the headline imply a causal association? 1. “Daily Exercise Improves Mental Performance” 2. “Want to lose weight? Eat more fiber!” 3. “Cat owners tend to be more educated than dog owners” Statistics: Unlocking the Power of Data Lock 5 Association and Causation ASSOCIATION IS NOT NECESSARILY CAUSAL! Come up with two variables that are associated , but not causally Come up with two variables that are causally associated Which is the explanatory variable? Which is the response variable? Statistics: Unlocking the Power of Data Lock 5 College Education and Aging “Education seems to be an elixir that can bring us a healthy body and mind throughout adulthood and even a longer life,” says Margie E. Lachman, a psychologist at Brandeis University who specializes in aging. For those in midlife and beyond, a college degree appears to slow the brain’s aging process by up to a decade, adding a new twist to the cost-benefit analysis of higher education for young students as well as those thinking about returning to school.” Are you convinced that a college degree slows the brain’s aging? a) Yes b) No People who go to college may have better brains to begin with! A Sharper Mind, Middle Age and Beyond -NY Times, 1/19/12 Statistics: Unlocking the Power of Data Lock 5 0 200 400 600 800 1000 40 50 60 70 80 TVs per 1000 People Life Expectancy Angola Australia Cambodia Canada China Egypt France Haiti Iraq Japan Madagascar Mexico Morocco Pakistan Russia South Africa Sri Lanka Uganda United Kingdom United States Vietnam Yemen r = 0.74 TVs and Life Expectancy Should you buy more TVs to live longer?

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