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NBME 21 Answers

nbme21/Block 4/Question#40 (reveal difficulty score)
A study is conducted to assess the normal ...
500 Men from a list of patients scheduled to be examined by a urologist 🔍 / 📺 / 🌳

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submitted by its_raining_jimbos(26),
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urO iltlte feidrn ash a orrvivuPas ieitcfon,n hhciw sifetcn todhrriey ,srcrueposr gcanusi rptnirutnieo fo erythrytoce .idntpucoro shiT is het smea wya it secasu drhyosp sltifea in runonb abibes and actlsaip amneia ni ksecil ,lcle .tce

submitted by seagull(1746),
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nmgxniEai eapnitt fomr a ioogrtlus eilmspi noreksB sBia hhcwi duwol eswk hte otnoauppil mean of erums reua norentig yaaw mfro the reut tuceaacr n.mae ,nThe rleeiaz oeinipsrc is tpenneded on tiaacsitslt erPow"" ihwhc is nicseared badse no eht sezi fo het lonapioptu of teh ust.dy esrcniae(d csprniioe = iarncseed iataltscsti .rewpo) ,reoefehrT na renscaie ni tnualopoip of a aisbde opurg with lade to yicncracau twhi gihh enic.ropsi

forerofore  to add up, the urologist himself doesn't add or remove accuracy (since this is a blood test), what decreases the accuracy is the fact that in order to be sent to a urologist you probably are sick in the first place (selection bias), so your urea nitrogen is likely to be altered. +25  
sharpscontainer  I thought of precision as more of a function of variance. Variance will decrease with a greater sample size. Had a hard time because I was thinking about those 4 darn targets (wouldn't 500 darts look more spread out than 10? but no, the variance will be better) that have been in my textbooks since 7th grade and for the first time I was asked a question about this concept only to discover that I didn't have it down as well as I assumed. +1  
peridot  @sharpscontainer I feel you, I thought the exact same thing. Looked into it a bit and I think it has something to do with the way standard error or standard deviation or something like that is calculated, but I'm still confused and too tired to dig further. Also, wanted to mention that this NBME has a similar question but instead it's about the 95% confidence interval - maybe that'll help you understand the precision thing better since the 95% confidence interval narrows with a larger sample size? So it's kinda tied to precision? +  

submitted by usmleuser007(435),
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.1 xmpElae of ceutiranac btu ihlghy ciseepr 
    a. 050 pttsneia ieensg a tacariplru otcrod rfo a ctluarapri sies.
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    .a 050 niaettsp gi(hh peico)risn nerodgu a rgsnciene ghih( acaurcyc ~ on saib or scsymite e)orr

submitted by drdoom(1045),
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aucAycrc seamn eht aadt iopsnt ear ers,ipsdde btu when ouy ktae the mena of soeht osp,nti ttah mean aep(s“ml a)mn”e si ayerbn teh nuoptoplai mena “(uetr n.”)aem tDaa iptnos ear o“emr esc”prie fi hte rpnsiesodi rocass tada nsipot si amrllse hatn moes heort ste of data otsinp (ocetni hwo sith si a incomasopr dan not an “lsub”oeta em;tat)tsne rocenipsi ssya nginhot tobua woh scelo teh veaeagr fo the tada tpions ear to eht uet“r a.nme”

Keep in dimn hatt crcaacuy nda rciespoin ear retlviae rsdcpits;ero ouy c’nat yas n“soda-o-s si ic;es”pre ,on ouy anc olyn say csasud“-nhhuc- is omer iesepcr ahnt ono”dsa-s- ro -“sasodn-o si roem cauctrea naht n-h”chudcassu-. S,o ni ihts saec, ew nac ernif tath BNEM ocnssredi m“ne ta eht tlgoosi”ru ot vhea UNBs that are lorces ot aehc roteh re(mo t;selurdce mreo csepie;r lses )edrdsisep anht hte BUsN fo ne“m ta .a”mll

’eseHr a ince :gmaei

submitted by cuthbertallg0od(13),
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Ducissisng ecisnirpo lyon ekmsa seesn fi yeth rewe to slmape X" # ts"iapnte mitluple mstei dna see owh lsceo the fitdneerf rmneesua'tsme srulste ewer ot ceha tre.ho The uaclta zeis of het smeapl duholst' aftfce ,escnpriio tub terarh ti udolhs sjtu tefcaf cyuraacc cwh(ih is rcedeud by the eadsib ptiloaonup ta hte oir)lo.stug mSh

submitted by ali_hassan(3),
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How deso 005 nme hitw irvsauo rcoiugolla sncnotdoii teslru in a receips emtesait? ldW'uton eth ayetvir of leuvas eud to soariuv eesderg fo ieslsnl dreeuc cornsipei dna usace a eirwd rteyiv?a

yMabe I reotthgvohu it

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