T H E K Ey S T Ro K E-l E V E 1 Model %r User Per%rmance Time with Interactwe Systems

There are ~ e g : N ms:poets of aser~emt,xu{er ~rforma~ce tha~ sys*em designers s h ~ d sys~emarka{~ ~ e r. This arlic|e prop~yses a ~im~}e m ~ e L the Neys{T{.>ke-Levd Medea, for predkd~g o,~e aspe~'t M w2rferma:mee: the t ime i:t takes ,a~ e x p e l u~wr ~;:o perform a givers *az~ m~ a give= eom,p~:{er sys{~a. The model is b.ae~ e~ counting keystrokes :a~d @~er |owdevel operatkms., i:~c{udir~g the user's ~me=taI ~re~aratioas arid the* system's re Pe e is coded fa ~¢~ge~ of ~e~e {~*rati~as an.d epe~a~r Nm¢~ s ~ : ~ Ce Nve Ne~c~i~s,~ HeurNfic n~}es are :gh'ef~ Nr p'redicti~g ~here men~al prelaara~ie~s ¢~ce~r. When tested against{ data ¢m 1|) diffe:re~ systems, ~N~I ' s pee~ic~ifye e ~ f N 2t ~ r e e m fee tMividual ~asks.. A= examNe N gia'ee m Rlus{ra{e h(~ NEe m ~ l .eaa ~ ~aed to pr~dece parametric predie{km.g add brow set~:sifivt{y aaaiysis c:a:a be ~:sexi m redeem ce~e|~.sfo~s in the face of ~mc,e~aia as:sumt~ti~o~:s, Finally, the model ~s e@m~ar~ ~o ~ereral s*mp|er ver,s&ms. "INe N, ter~fiaJ fete ~k~r ~he Keystroke*Level Model i.n gys{em de:skgn is N s~c:e:~se,d.. Key %V¢~,rds a~d Fvarase~: ~tmJa~<~a~mer N,terfaee, ~,:umara.e@eap~tef i~eraetkm, ~.er m¢~l , ~s~er ~ : e~/g:u~rive ~yeho~gy , erg s, :kmma:= fae'{o~rs~ ~y~ae:m,~ de~iga CR Ca~eg{~ri~es: 3L!~i, 4.6, 8.|