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How can you describe how far apart the responses are from the center in a data set? In this lesson you will learn how to describe the distribution of data by using the mean absolute deviation . MAD. First Let’s Review Reading a dot plot
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Howcanyoudescribehowfarapartthe responsesarefromthecenterinadataset? Inthislessonyouwilllearnhowto describethedistributionofdataby usingthemeanabsolutedeviation. MAD
First Let’sReview Readingadotplot Howmanybooksdid8thgradersatLilburnMiddleSchoolreadthissummer? 0 4 6 16 22 10 14 18 20 12 8 2 NumberofBooks
Let’sReview Themeanofasetofdataistheaverage. Howmanysiblingsdoyouhave? 5 4 1 0 2 3 0+0+0+1+1+1+2+2+3+4+5+5=24 24÷12=2
Let’sReview Absolutevalueisthedistanceanynumberis from0. |-5|=5 |3|=3
Variability: Describeshowthespreadoutorclosely clusteredthedatasetis. Thereare3waystodeterminethespread: 1.Range 2.InterquartileRange 3.MeanAbsoluteDeviation
ACommonMistake Themeanandmeanabsolutedeviationareoften confusedbecausetheybothincludetheword, “mean.” Meanabsolute deviation Mean
MeanAbsoluteDeviation(MAD): MAD-istheaveragedistancebetweeneach datavalueandthemean.
Findthemeanabsolutedeviation. Howmanysiblingsdoyouhave? 012345 Step1:Findthe 0 0 0 1 1 1 2 2 3 4 mean 5 +5 24÷12=2
Findthemeanabsolutedeviation. Howmanysiblingsdoyouhave? 2 2 2 1 1 1 0 0 0 1 2 3 4 5 1 2 3 3 3 12 2 2 2 1 1 1 0 0 3 Step2:Findthedistancebetween themeanandthevalues||
Remember: Staypositive! 6 5 32 lllllllllllllll 3 6 91215 6+3+2+5 4 MAD= =4
Findthemeanabsolutedeviation. Howmanysiblingsdoyouhave? 012345 2 2 2 1 1 1 0 0 1 2 3 3 3 2 2 2 1012 10 1 +3 1818÷12=1.5 of Step3:Findtheaverage thedistance.
You can alsoinformallycompare twopopulations byusingthemeanabsolute deviation(MAD).
NFCMAD: 6+33+45+24+21+15+12 7 =22.2 AFCMAD: 4+17+30+8+10+6+2 7 =11 Comparison The mean absolute deviation for the NFC is greater than the mean absolute deviation for the AFC. That means the data for penalties for the AFC are closer together. The NFC has a farther spread.
GuidedPractice – Try these two problems Findtherangeandmeanabsolutedeviation ofthisdata.
Findthemeanabsolutedeviation. Howmanypetsdoyouhave? 0,1,5,0,3,1,0,2,2,6
Race it!!!! Findtherangeandmeanabsolutedeviation ofthisdata. 6 4 10 12 8 2 NumberofCDsowned
Whatisthemeanabsolutedeviationofthe dataset? Howmanybooksdidyoureadthissummer? 3,5,2,3,3,1,4,4,3,2
Whatisthemeanabsolutedeviationofthe datasetandwhatdoesitmean? Howmanypairsofshoesdoyouown? 3,7,2,8,3,19,5,9
Findtherangeandmeanabsolutedeviation ofthis data. Howmanypairsofshoesdo8thgradersat LilburnMiddleSchoolown?