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Statistics: Unlocking the Power of DataLock5STAT 101Dr. Kari Lock MorganCollecting Data: ExperimentsSECTION 1.3•Association versus Causation•Confounding Variables•Observational Studies vs Experiments•Randomized Experiments
Statistics: Unlocking the Power of DataLock5AnnouncementsMy office hours this week are cancelled (I have a bad cold and don’t want to get anyone sick – sorry!). Feel free to email me with questions: [email protected]TA office hours (in Old Chem 211A):Yating Gu: Thurs 5 – 7pmTori Hall: Sun 4 – 6pmDavid Clancy: Sun 7 – 9pmStephanie Sun: Mon 4 – 6pmMao Hu: Tues 7 – 9pmStat Ed Center (Old Chem 211A): Sun-Thurs 4 – 9pm
Statistics: Unlocking the Power of DataLock5Voluntary SurveyStudy on improving student self-confidence in STEM fields (voluntary, prizes available):
Statistics: Unlocking the Power of DataLock5ReviewIf sampling bias exists, we cannot make generalizations from the sample to the populationTaking a random sample avoids sampling biasEven if sampling bias is avoided, bias may enter the data in other forms (wording, context, inaccurate responses, etc.)Always think critically about how the data were collected,
Statistics: Unlocking the Power of DataLock5DATAData Collection and BiasPopulationSampleTODAY
Statistics: Unlocking the Power of DataLock5Explanatory and ResponseIf we are using one variable to help us understand or predict values of another variable, we call the former the explanatory variableand the latter the response variableExamples:Does meditation help reduce stress?Does sugar consumption increase hyperactivity?
Statistics: Unlocking the Power of DataLock5Association and CausationTwo variables are associated if values of one variable tend to be related to values of the other variableTwo variables are causally associated if changing the value of the explanatory variable influences the value of the response variable
Statistics: Unlocking the Power of DataLock5Explanatory, Response, CausationFor each of the following headlines:Identify the explanatory and response variables (if appropriate).Does the headline imply a causalassociation?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 DataLock5Association and CausationASSOCIATION IS NOT NECESSARILY CAUSAL!Come up with two variables that are associated, but not causallyCome up with two variables that are causally associatedWhich is the explanatory variable?Which is the response variable?
Statistics: Unlocking the Power of DataLock5College 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