Experimental DesignExperimental Design

ObservationObservation

Something you experience that makes you Something you experience that makes you wonder and ask questions.wonder and ask questions.

Hmm. . . I heard a rumor that there is a Hmm. . . I heard a rumor that there is a ringtone that adults cannot hearringtone that adults cannot hear

Ask a questionAsk a question

Either ask a question or state a problemEither ask a question or state a problem

Can adults really not hear certain ringtones?Can adults really not hear certain ringtones?

HypothesisHypothesis

A A tentative testabletentative testable predictionprediction of your of your observations based on prior experiencesobservations based on prior experiences

Format:Format:If. . . If. . .

then . . . then . . .

because. . .because. . . age affects the frequency people can hear

we play the ringtone for different agesolder people won’t hear the higher frequency ringtone

ExperimentsExperiments

Tests hypothesisTests hypothesis

Must be controlled – only one variable is Must be controlled – only one variable is purposefully changedpurposefully changed

Ten people of Ten people of different agesdifferent ages are in the same are in the same room at the same time and are exposed to room at the same time and are exposed to the mosquito ringtone from the same the mosquito ringtone from the same phone. phone.

Parts of Controlled ExperimentParts of Controlled Experiment

Independent Variable – variable that is Independent Variable – variable that is changed by the experimenterchanged by the experimenter

Dependent Variable – variable that changes Dependent Variable – variable that changes in response to the independent variable in response to the independent variable (what is measured)(what is measured)

Independent variable: AgeIndependent variable: AgeDependent variable: if they hear the ringtoneDependent variable: if they hear the ringtone

Parts of Controlled ExperimentParts of Controlled Experiment

Control Group – group that is used for comparison Control Group – group that is used for comparison (normal group)(normal group)

Constants – parts of the experiment that remain Constants – parts of the experiment that remain the same for all trialsthe same for all trials

Control Group – young people who hear the Control Group – young people who hear the ringtoneringtone

Constants – Same room, same time, same phone, Constants – Same room, same time, same phone, same volume, same ringtonesame volume, same ringtone

Record Data & AnalyzeRecord Data & AnalyzeQualitative data – word descriptionsQualitative data – word descriptionsQuantitative data – numerical descriptionsQuantitative data – numerical descriptionsAnalysis of data – looking for patterns, applying Analysis of data – looking for patterns, applying

mathematical models, graphingmathematical models, graphing

Qualitative data – some adults don’t react when Qualitative data – some adults don’t react when phone ringsphone rings

Quantitative data – 4 of the 5 people under 18 Quantitative data – 4 of the 5 people under 18 hear ringtone while only 1 of the 5 people 18 hear ringtone while only 1 of the 5 people 18 and older hear the ringtoneand older hear the ringtone

Analysis of data – see graphAnalysis of data – see graph

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Under 18 18 and Older

Age of Listener (years)

Num

ber o

f peo

ple

who

can

he

ar th

e rin

gton

eThe Effectiveness of Mosquito Ringtones

ConclusionConclusion

Reject or accept hypothesis based on Reject or accept hypothesis based on resultsresults

Based on our results, we would accept our Based on our results, we would accept our hypothesishypothesis

So now what?So now what?

Did we just make a new theory or law?Did we just make a new theory or law?

NO.NO. Theories are a set of related Theories are a set of related hypotheses that have been tested and hypotheses that have been tested and confirmed many times by many scientists. confirmed many times by many scientists. Laws state rules of nature and are Laws state rules of nature and are explained by theories.explained by theories.