Scientific Scientific MethodMethod

Independent Variable Independent Variable ((IVIV))

what you what you changechange in the in the experimentexperiment

this this ““changechange”” needs to be needs to be measurablemeasurableexamplesexamples

weightweightmassmassvolumevolumeheightheight

Dependent Variable Dependent Variable ((DVDV))

the the resultresult from the change from the change you madeyou made

what you what you measuremeasure known asknown as datadata““dependsdepends”” on your on your independentindependent variablevariable

also should be measurablealso should be measurable

The IV and DVThe IV and DV … …are close relatives and can are close relatives and can be found throughout the be found throughout the following steps of the following steps of the scientific process:scientific process:

ASK A ASK A QUESTIONQUESTION FORM A FORM A HYPOTHESISHYPOTHESISTEST TEST THE HYPOTHESISTHE HYPOTHESISANALYZE THE ANALYZE THE RESULTSRESULTS/DATA/DATA

Ask a Ask a QuestionQuestion

Ask a Ask a QuestionQuestion

Does theDoes the _________________________

((Ind.Var. -IVInd.Var. -IV))

   affect theaffect the

________________________??

((Dep.Var. - DVDep.Var. - DV))

Form a Form a HypothesisHypothesis 

Form a Form a HypothesisHypothesis

Hypothesis Hypothesis a measurable and a measurable and educated educated guessguesspredictspredicts how the independent how the independent variable willvariable will affectaffect the dependent the dependent variablevariable

Form a Form a HypothesisHypothesis If theIf the __________________________ isis

_____________,_____________,

((Ind.Var. - IVInd.Var. - IV)) ((incr./decr.incr./decr.))

then thethen the ________________________ willwill ___________.___________.

((Dep. Var. - DVDep. Var. - DV) ) ((incr./decr./incr./decr./

stay stay the samethe same))

Test the Test the HypothesisHypothesis 

Test the Test the HypothesisHypothesis

Data TableData Tablean an organized organized way to record way to record datadata

IndependeIndependent Variable nt Variable

– IV– IV

Dependent Variable Dependent Variable - DV- DV

Test the Test the HypothesisHypothesis

Data TableData Table

Trial Trial OneOne

TrialTrial TwoTwo

Trial Trial ThreeThree

AveragAveragee

(Mean)(Mean)

Analyze Analyze the Resultsthe Results

Analyze the Analyze the ResultsResults

Results Results patternspatterns and and relationships relationships between what you are between what you are changing (changing (IVIV) and your data ) and your data ((DVDV))

Analyze the Analyze the ResultsResults

Types of ResultsTypes of Resultsquantitative: quantitative: numbersnumbers, ,

amounts, measurements, etc.amounts, measurements, etc.raw raw datadata

qualitative: qualitative: comparisonscomparisons, , relationships, etc.relationships, etc.examplesexamples

bigger/smallerbigger/smallerthicker/thinnerthicker/thinnerbrighter/more dullbrighter/more dull

Analyze the Analyze the ResultsResults

Line GraphLine Graphrepresents represents patterns and patterns and relationships between what relationships between what you are changing (IV) and your you are changing (IV) and your data (DV)data (DV)

Analyze the Analyze the ResultsResults

Line Graph TitleLine Graph TitleThe effect of theThe effect of the

..

((Independent Variable Independent Variable

– IV– IV))

on the on the ..

((Dependent Variable - DVDependent Variable - DV))

Independent Independent Variable - IVVariable - IV

Dep

en

den

t D

ep

en

den

t V

ari

ab

le -

DV

Vari

ab

le -

DV

Analyze the Analyze the ResultsResults

Line Graph Set-up …Line Graph Set-up …(…title goes here – across the top)(…title goes here – across the top)

Analyze the Analyze the ResultsResults

Writing your resultsWriting your resultsState theState the datadataConcentrate on the Concentrate on the averagesaveragesQuantitative –Quantitative – numbersnumbers

means, minimum, maximum, means, minimum, maximum, range, etc.range, etc.

Qualitative –Qualitative – comparecompare the the resultsresultsuse words like use words like ““fasterfaster””, , ““largerlarger””, , ““lessless””, , ““greatergreater””, etc., etc.

Draw Draw ConclusionConclusion

ss

Draw Draw ConclusionsConclusions

ConclusionConclusionrestaterestate the hypothesis the hypothesisdecidedecide if your hypothesis was if your hypothesis was supportedsupported

restate the restate the datadatadiscuss possible sources of discuss possible sources of error (error (SOESOE’’ss))

discuss discuss futurefuture applications applications

Draw Draw ConclusionsConclusions

Sources of Error (Sources of Error (SOESOE’’ss))possible changes in possible changes in materials materials that could that could alteralter the results of the results of the experimentthe experimentoften a result of having too many often a result of having too many variablesvariables

all materials other than the all materials other than the independent variable should independent variable should remain remain constantconstant

Draw Draw ConclusionsConclusions

ConstantsConstantsall factors in an experiment all factors in an experiment that are kept the that are kept the samesamean experiment should only test an experiment should only test ONE factor – your ONE factor – your independent independent variablevariable

Draw Draw Conclusions Conclusions Writing a ConclusionWriting a Conclusion

Begin with “The hypothesis stated “If the …”Next, “The data did/did not support the hypothesis.”Then, explain what the data shows.Discuss possible SOE’s and how you could improve your experiment (and avoid these SOE’s) next time.Compare to the control.

Draw Draw ConclusionsConclusions

ControlControlthe normal the normal expectationexpectation of what of what is to happenis to happenwhat you what you compare compare your results your results totoexample: If you wanted to see if example: If you wanted to see if fertilizer would increase a plantfertilizer would increase a plant’’s s growth rate you would have several growth rate you would have several different plants receiving different different plants receiving different amounts of fertilizer, but your amounts of fertilizer, but your control would just receive water, control would just receive water, and no fertilizer.and no fertilizer.

CommunicCommunicateResultsateResults

CommunicateResCommunicateResultsultsWrite a Write a lab reportlab report

Publish an Publish an articlearticle in a in a scientific journalscientific journalWrite a Write a bookbook

RememberRemember……

You must see theYou must see the INDEPENDENT VARIABLEINDEPENDENT VARIABLE and and

the the DEPENDENT VARIABLEDEPENDENT VARIABLE

when youwhen you … …ASK aASK a QUESTIONQUESTION

FORM a HYPOTHESISFORM a HYPOTHESIS

TEST the HYPOTHESISTEST the HYPOTHESISin the DATA TABLES,in the DATA TABLES, and and

ANALYZE the RESULTS/DATAANALYZE the RESULTS/DATA in the LINE GRAPHin the LINE GRAPH