SECTION 1.3 - Section 1.3 Experiments and Observational...

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Statistics: Unlocking the Power of DataLock5Section 1.3Experiments and Observational Studies
Statistics: Unlocking the Power of DataLock5OutlineAssociation versus CausationConfounding VariablesObservational Studies vs ExperimentsRandomized Experiments
Statistics: Unlocking the Power of DataLock5DATAData Collection and BiasPopulationSampleTODAY
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 DataLock5Causal Association?The wording of this headline implies…a)Association (not necessarily causal)b)Causal Association“Daily Exercise Improves Mental Performance”
Statistics: Unlocking the Power of DataLock5Causal Association?The wording of this headline implies…a)Association (not necessarily causal)b)Causal Association“Cat owners tend to be more educated than dog owners”
Statistics: Unlocking the Power of DataLock5020040060080010004050607080TVs per 1000 PeopleLife ExpectancyAngolaAustraliaCambodiaCanadaChinaEgyptFranceHaitiIraqJapanMadagascarMexicoMoroccoPakistanRussiaSouth AfricaSri LankaUgandaUnited KingdomUnited StatesVietnamYemenr = 0.74TVs and Life ExpectancyShould you buy more TVs to live longer?Association does not imply causation!
Statistics: Unlocking the Power of DataLock5Confounding VariableA third variable that is associated with both the explanatory variable and the response variable is called a confounding variableA confounding variable can offer a plausible explanation for an association between the explanatory and response variablesWhenever confounding variables are present (or may be present), a causal association cannot be determined
Statistics: Unlocking the Power of DataLock5Confounding VariableExplanatory VariableResponse VariableConfounding Variable
Statistics: Unlocking the Power of DataLock5TVs and Life ExpectancyNumber of TVs per capitaLife ExpectancyWealth
Statistics: Unlocking the Power of DataLock5Confounding VariableFor each of the following relationships, identify a possible confounding variable:1.More ice cream sales have been linked to more deaths by drowning.2.The total amount of beef consumed and the total amount of pork consumed worldwide are closely related over the past 100 years.

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