# Designing an Experiment The Scientific Method A problem solving technique based on a logical progression of steps State the Problem Gather info Propose.

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Designing an Experiment

The Scientific Method A problem solving technique based on a logical progression of steps State the Problem Gather info Propose a hypothesis Test a hypothesis Analyze data Conclusion

I have a great idea! As a scientist working for Exxon, I want to prove Exxon gets better mileage than Lukoil! Let’s design an experiment!

Gather info

Lukoil experiment Drive the Hummer up Mt Pocono Drive as fast as you can Fill a Hummer with Lukoil gas.

Exxon experiment Drive the SmartCar DOWN Mt Pocono Drive as slow as you can Fill a SmartCar with Exxon gas.

Analyze Data Lukoil = 1 mi/gal Exxon = 100 mi/gal Let’s make some commercials and sell some Exxon!!!

Fair Experiment? bias Favoritism, or prejudice towards a certain outcome Where does bias come from? Past experience Personal gain Peer pressure

Variables in an experiment Variable – factor which changes How many variables should a “fair” experiment have?

Variables in an experiment You need to change ONE thing at a time Then do the experiment and see what happens.

Variables in an experiment You need to change ONE thing at a time Then do the experiment and see what happens. Independent Variable Dependent Variable

Variables in an experiment Independent Variable The factor in an experiment you are attempting to test Dependent Variable The factor you measure in order to determine the effect of the independent variable

Variables in an experiment Controlled Variables The factors in an experiment you try to keep the same throughout the experiment These are sometimes called controls.

Independent variables answer the question "What do I change?". Dependent variables answer the question "What do I observe?". Controlled variables answer the question "What do I keep the same?"

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