QuadraticRegressionUsingtheNspireGraphingCalculator
Wewillusethefollowingdatatodoaregressionequationonourgraphingcalculator:
Agolfballishitdownastraightfairway.Thefollowingtableshowstheheightoftheballatcertaintime
intervals.Howcanwefindoutwhentheballreachesitsmaximumheight?Howcanwepredicthowlongitwill
taketoland?Acalculatorwillallowustofindanequationthatmatchesthisdata,thenwecanuseittoanswer
thesequestions!
Time
0
.5
1
1.5
2
2.5
3
3.5
4
4.5
Height
0
17.2
31.5
42.9
51.6
57.7
61.2
62.3
61.0
57.2
First,graphthedatabyhandonyourworksheetandpredictwhattypeofequationwe’llneedtofitthedata.
1) UsingtheNSpireGraphingCalculatortoEnterandGraphData.
Select1:NewDocument
PressEnter.
Select4:AddLists&Spreadsheet
PressEnter.
2)
Makesurethatasyoutypeintheheadingsofeachcolumnyouareintheverytoppartofthecolumns.
PressEnteraftereachheadingiscomplete.Putthecursorinthefirstrowofthespreadsheettostartentering
thedata.
Enterallthedatafromyourtable.
PleaseNote:Youcannotseeallthedatainthescreenshot.
3)
MakingaScatterPlotoftheDataontheNSpireGraphingCalculator
InsertanewpagebypressingtheControlKey(ctrl)andtheDocKey.
Select5:AddData&Statistics
PressEnter.
1
Noticethemessageatthebottomofthescreenandtheleftpartofthescreen:
“ClickorEntertoaddvariable”.
Movethecursortothismessageon Movethecursortothismessageon PressEnter.
thex-axis.
they-axis.Themessagemaynot
PressEnter.
appearrightawayuntilthecursor
Selecttime.
getsclosetoit.
PressEnter.
Selectheight.
4)Whattypeoffunctiondoesthisappeartobe?(writeonyourworksheet)
5)FindingaRegressionEquationontheCalculator–showingonthegraph
PressMenu.
Select4:Analyze
UsetherightarrowontheTouchPadandselect6:Regression.
UsetherightarrowontheTouchPadandselect
4:Showquadratic
PressEnter.
Writethequadraticfunctionthatisshown(roundtothenearesttenth).
(NOTE:Ifyouneedtomovetheequationtoseeit,movethehandoverit,thenclickandholdwiththecenter
buttonuntilthehandcloses.Thenyoucandragtheequation.)
2
6)FindingaRegressionEquationontheCalculatorusingtheListsandSpreadsheets
Push“Ctrl”“leftarrow”togetbacktopage1.
Placethecursorinthefirstrowofcolumnc
PressMenu
Choose4:Statistics
Choose1:StatCalculations
Choose6:QuadraticRegression
Apopupmenuwillappear(seebelow)
Choose:timeforxlist
Heightforylist
Everythingelseshouldbefine–clickok,orenter.
Recordtheequationfromthedata–rememberf(x)=ax2+bx+c
7)Inthelistofinformation,findthe“R2”number._____
Ifthisnumberisreallycloseto1(like0.98,1.03…)thenyourequationisagoodfitfor
thisdata.Isthisequationagoodfitforthedata?
8)Usingtheequationyoufoundabove,determinewhattimethegolfballwillhitthe
ground.
3