All negative values (e.g., -998 ) are coded as missing. Please check if this is ok!

ORDLESING

We have a total of 431 items. The the number of observations per item:
item1 observation1 item2 observation2 item3 observation3
B3_ord03s 786 B3_av591s 353 B3_av809s 252
B3_ord04s 786 B3_av781s 417 B3_av083s 252
B3_ord05s 786 B3_av060s 353 B3_av183s 252
B3_ord07s 786 B3_av068s 353 B3_av247s 483
B3_ord08s 786 B3_av220s 605 B3_av227s 252
B3_ord93s 786 B3_av248s 417 B3_av195s 252
B3_ord88s 786 B3_av244s 353 B3_av263s 252
B3_ord86s 525 B3_av252s 584 B3_av311s 252
B3_ord10s 525 B3_av324s 655 B3_av813s 252
B3_ord11s 525 B3_av388s 417 B3_av387s 252
B3_ord12s 525 B3_av400s 417 B3_av503s 483
B3_ord46s 525 B3_av432s 353 B3_av499s 252
B3_ord72s 525 B3_av444s 353 B3_av723s 252
B3_ord70s 525 B3_av532s 353 B3_av651s 252
B3_ord74s 655 B3_av572s 417 B3_av631s 252
B3_ord76s 655 B3_av596s 417 B3_av615s 252
B3_ord65s 655 B3_av620s 353 B3_av817s 252
B3_ord33s 265 B3_av660s 353 B3_av124s 252
B3_ord79s 265 B3_av672s 353 B3_av116s 252
B3_ord49s 265 B3_av652s 353 B3_av224s 252
B3_ord81s 265 B3_av021s 353 B3_av156s 252
B3_ord35s 452 B3_av025s 353 B3_av160s 252
B3_ord63s 452 B3_av077s 64 B3_av280s 252
B3_ord02s 452 B3_av233s 64 B3_av272s 252
B3_ord50s 452 B3_av257s 64 B3_av304s 252
B3_ord67s 452 B3_av074s 64 B3_av348s 252
B3_ord68s 452 B3_av082s 64 B3_av396s 252
B3_ord32s 452 B3_av254s 64 B3_av468s 252
B3_ord77s 353 B3_av246s 64 B3_av488s 252
B3_ord78s 353 B3_av226s 64 B3_av464s 252
B3_ord56s 353 B3_av278s 64 B3_av552s 252
B3_ord66s 353 B3_av442s 64 B3_av560s 252
B3_ord51s 353 B3_av458s 64 B3_av700s 252
B3_ord45s 353 B3_av570s 64 B3_av580s 252
B3_ord62s 353 B3_av606s 64 B3_av604s 252
B3_ord71s 332 B3_av006s 295 B3_av105s 466
B3_ord80s 332 B3_av019s 302 B3_av053s 466
B3_av753s 356 B3_av027s 64 B3_av113s 238
B3_av013s 356 B3_av087s 64 B3_av145s 238
B3_av141s 356 B3_av785s 64 B3_av022s 238
B3_av181s 356 B3_av091s 64 B3_av050s 238
B3_av166s 903 B3_av143s 533 B3_av158s 238
B3_av038s 356 B3_av147s 278 B3_av186s 238
B3_av042s 356 B3_av199s 64 B3_av190s 238
B3_av150s 356 B3_av223s 278 B3_av274s 238
B3_av194s 356 B3_av159s 295 B3_av282s 238
B3_av206s 356 B3_av751s 64 B3_av366s 238
B3_av266s 356 B3_av251s 64 B3_av534s 238
B3_av757s 356 B3_av303s 64 B3_av538s 238
B3_av302s 356 B3_av789s 64 B3_av031s 452
B3_av354s 356 B3_av355s 64 B3_av011s 238
B3_av462s 356 B3_av395s 64 B3_av009s 238
B3_av470s 356 B3_av623s 64 B3_av047s 238
B3_av239s 903 B3_av531s 533 B3_av821s 238
B3_av059s 356 B3_av515s 64 B3_av219s 469
B3_av131s 356 B3_av635s 64 B3_av163s 452
B3_av139s 356 B3_av096s 64 B3_av243s 238
B3_av111s 356 B3_av793s 64 B3_av295s 469
B3_av123s 356 B3_av104s 64 B3_av335s 469
B3_av761s 356 B3_av188s 64 B3_av825s 469
B3_av155s 356 B3_av184s 64 B3_av379s 238
B3_av175s 587 B3_av196s 64 B3_av431s 238
B3_av259s 356 B3_av232s 64 B3_av475s 238
B3_av255s 594 B3_av332s 64 B3_av523s 238
B3_av235s 356 B3_av392s 64 B3_av555s 238
B3_av187s 570 B3_av428s 64 B3_av595s 238
B3_av271s 356 B3_av384s 64 B3_av120s 238
B3_av275s 356 B3_av472s 64 B3_av829s 469
B3_av279s 570 B3_av476s 64 B3_av092s 238
B3_av343s 356 B3_av508s 64 B3_av152s 238
B3_av765s 356 B3_av520s 64 B3_av172s 238
B3_av299s 356 B3_av524s 64 B3_av228s 469
B3_av307s 570 B3_av556s 64 B3_av260s 238
B3_av399s 587 B3_av568s 64 B3_av308s 469
B3_av583s 356 B3_av600s 64 B3_av408s 238
B3_av599s 356 B3_av061s 64 B3_av452s 469
B3_av467s 356 B3_av069s 64 B3_av456s 469
B3_av547s 356 B3_av117s 72 B3_av584s 238
B3_av551s 356 B3_av217s 72 B3_av608s 238
B3_av563s 356 B3_av153s 72 B3_av624s 238
B3_av316s 903 B3_av066s 72 B3_av640s 238
B3_av769s 356 B3_av054s 72 B3_av656s 469
B3_av012s 356 B3_av210s 72 B3_av664s 238
B3_av020s 356 B3_av146s 72 B3_av085s 238
B3_av148s 356 B3_av178s 72 B3_av093s 238
B3_av200s 587 B3_av262s 72 B3_av193s 231
B3_av212s 570 B3_av310s 72 B3_av014s 231
B3_av216s 356 B3_av342s 72 B3_av090s 231
B3_av284s 356 B3_av486s 72 B3_av182s 231
B3_av312s 356 B3_av494s 72 B3_av242s 231
B3_av380s 570 B3_av099s 72 B3_av338s 231
B3_av368s 356 B3_av071s 72 B3_av394s 231
B3_av125s 903 B3_av063s 72 B3_av378s 231
B3_av416s 356 B3_av039s 72 B3_av035s 231
B3_av420s 570 B3_av797s 72 B3_av095s 231
B3_av424s 356 B3_av015s 72 B3_av115s 231
B3_av436s 570 B3_av151s 324 B3_av833s 231
B3_av480s 356 B3_av171s 324 B3_av331s 231
B3_av484s 356 B3_av231s 286 B3_av367s 231
B3_av496s 356 B3_av267s 324 B3_av435s 231
B3_av500s 587 B3_av283s 72 B3_av459s 231
B3_av504s 428 B3_av323s 72 B3_av471s 231
B3_av516s 356 B3_av801s 324 B3_av479s 231
B3_av133s 903 B3_av327s 324 B3_av519s 231
B3_av528s 587 B3_av663s 324 B3_av571s 231
B3_av536s 356 B3_av643s 72 B3_av659s 231
B3_av540s 356 B3_av619s 72 B3_av028s 231
B3_av544s 356 B3_av575s 72 B3_av088s 231
B3_av287s 903 B3_av559s 72 B3_av236s 231
B3_av005s 356 B3_av671s 72 B3_av180s 231
B3_av007s 356 B3_av805s 324 B3_av344s 231
B3_av029s 353 B3_av108s 72 B3_av300s 231
B3_av157s 353 B3_av080s 72 B3_av356s 231
B3_av221s 353 B3_av164s 324 B3_av376s 231
B3_av034s 353 B3_av192s 72 B3_av065s 231
B3_av046s 353 B3_av256s 72 B3_av708s 231
B3_av162s 353 B3_av208s 72 B3_av636s 231
B3_av170s 353 B3_av296s 324 B3_av576s 231
B3_av230s 353 B3_av336s 324 B3_av632s 231
B3_av330s 353 B3_av340s 72 B3_av109s 231
B3_av390s 353 B3_av352s 324 B3_av121s 231
B3_av506s 353 B3_av548s 324 B3_av169s 231
B3_av554s 353 B3_av564s 72 B3_av023s 214
B3_av119s 353 B3_av592s 72 B3_av391s 214
B3_av107s 353 B3_av616s 72 B3_av443s 214
B3_av075s 353 B3_av129s 72 B3_av423s 214
B3_av051s 584 B3_av137s 72 B3_av383s 214
B3_av055s 353 B3_av073s 466 B3_av699s 214
B3_av773s 353 B3_av177s 466 B3_av535s 214
B3_av179s 655 B3_av249s 466 B3_av483s 214
B3_av215s 353 B3_av008s 466 B3_av495s 214
B3_av211s 584 B3_av098s 466 B3_av487s 214
B3_av207s 567 B3_av218s 466 B3_av539s 214
B3_av191s 353 B3_av258s 466 B3_av507s 214
B3_av375s 353 B3_av154s 466 B3_av455s 214
B3_av347s 417 B3_av414s 466 B3_av044s 214
B3_av777s 417 B3_av430s 466 B3_av072s 214
B3_av351s 353 B3_av750s 466 B3_av176s 214
B3_av427s 353 B3_av530s 466 B3_av144s 214
B3_av639s 353 B3_av542s 466 B3_av460s 214
B3_av655s 353 B3_av043s 252 B3_av268s 214
B3_av607s 353 B3_av067s 252 B3_av748s 214
B3_av567s 353 B3_av079s 466 B3_av644s 214
B3_av579s 417 B3_av103s 466 NA NA

Level of difficulty

We have 431 dichotomous items, and 0 polytomous items. Here is the the distribution of percentage correct for the dichotomous items:

The items were never answered incorrectly, and are removed from further analysis.

Also, 1762 students did not receive any items from this category.

IRT

The resulting test information curve is as follows:

Item parameters a (discrimination) and d (difficulty)
a d
B3_ord03s 1.1 -3.4
B3_ord04s 1.0 -3.1
B3_ord05s 0.7 -3.1
B3_ord07s 1.1 -3.1
B3_ord08s 0.7 -2.5
B3_ord93s 0.7 -2.4
B3_ord88s 1.0 -2.5
B3_ord86s 0.5 -5.9
B3_ord10s 0.6 -4.0
B3_ord11s 0.8 -2.8
B3_ord12s 1.0 -2.2
B3_ord46s 0.8 -3.9
B3_ord72s 0.9 -3.8
B3_ord70s 1.0 -2.1
B3_ord74s 0.8 -0.7
B3_ord76s 1.6 -1.6
B3_ord65s 1.3 -1.4
B3_ord33s 1.3 -2.1
B3_ord79s 1.4 -2.0
B3_ord49s 1.1 -2.3
B3_ord81s 2.1 -1.6
B3_ord35s 0.9 -2.2
B3_ord63s 0.3 -11.7
B3_ord02s 0.9 -2.6
B3_ord50s 1.2 -2.4
B3_ord67s 1.1 -2.5
B3_ord68s 1.1 -1.9
B3_ord32s 0.7 -3.3
B3_ord77s 0.8 -3.1
B3_ord78s 0.7 -3.7
B3_ord56s 0.8 -3.6
B3_ord66s 0.7 -3.5
B3_ord51s 0.7 -3.7
B3_ord45s 0.8 -1.9
B3_ord62s 0.8 -2.9
B3_ord71s 0.4 -6.8
B3_ord80s 0.9 -3.2
B3_av753s 1.2 -1.7
B3_av013s 1.6 -1.5
B3_av141s 1.7 -1.5
B3_av181s 1.8 -1.3
B3_av166s 1.7 -1.2
B3_av038s 1.9 -1.3
B3_av042s 1.6 -1.2
B3_av150s 1.8 -1.0
B3_av194s 1.7 -1.2
B3_av206s 1.5 -1.5
B3_av266s 1.9 -1.1
B3_av757s 1.4 -2.6
B3_av302s 1.5 -0.5
B3_av354s 1.6 -0.7
B3_av462s 1.9 -0.8
B3_av470s 1.5 -0.4
B3_av239s 1.4 -1.2
B3_av059s 1.9 -0.8
B3_av131s 2.0 -1.2
B3_av139s 2.0 -1.0
B3_av111s 1.4 -1.3
B3_av123s 2.3 -0.9
B3_av761s 1.5 -2.3
B3_av155s 1.7 -0.7
B3_av175s 2.2 -1.0
B3_av259s 1.9 -1.0
B3_av255s 1.4 -0.8
B3_av235s 2.2 -0.8
B3_av187s 2.0 -0.5
B3_av271s 2.0 -0.8
B3_av275s 1.4 0.3
B3_av279s 1.5 -0.7
B3_av343s 2.2 -0.9
B3_av765s 1.6 -2.2
B3_av299s 1.7 -0.7
B3_av307s 1.7 -0.2
B3_av399s 1.5 0.1
B3_av583s 2.3 -0.7
B3_av599s 2.0 -0.3
B3_av467s 1.6 -0.2
B3_av547s 1.6 -0.4
B3_av551s 1.1 0.5
B3_av563s 1.8 -0.6
B3_av316s 1.6 -0.6
B3_av769s 2.0 -1.7
B3_av012s 1.5 -0.8
B3_av020s 1.9 -1.1
B3_av148s 1.8 -0.8
B3_av200s 1.9 -0.5
B3_av212s 1.8 -1.1
B3_av216s 2.4 -0.7
B3_av284s 2.4 -0.7
B3_av312s 1.8 -0.5
B3_av380s 1.9 -0.7
B3_av368s 1.0 0.9
B3_av125s 1.6 -1.9
B3_av416s 1.5 0.0
B3_av420s 2.0 0.0
B3_av424s 2.0 -0.6
B3_av436s 1.9 -0.2
B3_av480s 1.5 -0.5
B3_av484s 1.7 -0.3
B3_av496s 1.6 -0.4
B3_av500s 1.4 0.0
B3_av504s 1.1 0.4
B3_av516s 1.2 0.0
B3_av133s 1.6 -1.7
B3_av528s 0.5 1.0
B3_av536s 1.1 0.6
B3_av540s 1.1 0.8
B3_av544s 1.1 0.2
B3_av287s 1.6 -0.2
B3_av005s 1.7 -1.5
B3_av007s 1.9 -1.1
B3_av029s 1.7 -1.5
B3_av157s 1.5 -1.3
B3_av221s 1.6 -1.0
B3_av034s 1.7 -1.5
B3_av046s 1.5 -1.4
B3_av162s 2.0 -1.2
B3_av170s 1.7 -1.3
B3_av230s 1.8 -1.0
B3_av330s 1.7 -0.9
B3_av390s 1.5 -0.9
B3_av506s 1.8 0.4
B3_av554s 1.7 -0.2
B3_av119s 2.0 -0.6
B3_av107s 2.1 -0.5
B3_av075s 1.5 -1.0
B3_av051s 1.5 -1.2
B3_av055s 1.9 -1.1
B3_av773s 1.3 -2.0
B3_av179s 1.6 -1.2
B3_av215s 1.8 -1.1
B3_av211s 1.6 -1.3
B3_av207s 2.0 -1.1
B3_av191s 1.8 -1.0
B3_av375s 1.8 -1.0
B3_av347s 1.7 -0.8
B3_av777s 1.2 -1.9
B3_av351s 2.3 -0.7
B3_av427s 1.2 -1.1
B3_av639s 1.3 -0.6
B3_av655s 1.3 -0.4
B3_av607s 2.2 -0.8
B3_av567s 0.7 1.0
B3_av579s 1.7 -0.6
B3_av591s 0.8 -0.3
B3_av781s 1.9 -1.5
B3_av060s 1.6 -0.6
B3_av068s 1.2 -1.3
B3_av220s 1.7 -0.4
B3_av248s 1.6 -0.6
B3_av244s 1.4 -0.8
B3_av252s 2.0 -0.2
B3_av324s 1.5 -0.3
B3_av388s 1.1 0.4
B3_av400s 1.6 0.3
B3_av432s 1.7 0.2
B3_av444s 1.3 -0.3
B3_av532s 0.8 0.5
B3_av572s 1.4 1.1
B3_av596s 0.6 0.4
B3_av620s 0.9 1.3
B3_av660s 1.0 -0.5
B3_av672s 1.4 -0.2
B3_av652s 1.0 1.7
B3_av021s 1.6 -1.4
B3_av025s 1.5 -1.3
B3_av077s 0.1 -7.1
B3_av233s 1.5 -1.7
B3_av257s 2.1 -1.3
B3_av074s 1.1 -2.1
B3_av082s 0.8 -3.3
B3_av254s 1.4 -1.0
B3_av246s 1.4 -1.0
B3_av226s 1.6 -1.4
B3_av278s 1.5 -0.6
B3_av442s 1.4 -0.7
B3_av458s 2.1 -0.6
B3_av570s 1.6 0.6
B3_av606s 1.5 -1.6
B3_av006s 1.4 -1.2
B3_av019s 1.5 -1.3
B3_av027s 1.8 -0.7
B3_av087s 1.0 -1.6
B3_av785s 5.1 -2.4
B3_av091s 0.6 -3.0
B3_av143s 1.8 -1.0
B3_av147s 1.4 -1.3
B3_av199s 2.3 -0.8
B3_av223s 1.6 -0.8
B3_av159s 1.2 -1.1
B3_av751s 2.3 -0.1
B3_av251s 0.8 -0.7
B3_av303s 1.6 -0.1
B3_av789s 0.3 -7.8
B3_av355s 2.2 -0.5
B3_av395s 1.6 -0.8
B3_av623s 1.7 -0.1
B3_av531s 1.0 -0.1
B3_av515s 2.2 -0.7
B3_av635s 1.3 0.5
B3_av096s 1.2 -0.9
B3_av793s 1.1 -3.1
B3_av104s 1.7 -0.8
B3_av188s 2.5 -0.3
B3_av184s 1.5 -0.7
B3_av196s 2.3 -0.6
B3_av232s 2.3 -0.2
B3_av332s 1.4 -0.8
B3_av392s 0.9 -0.3
B3_av428s 1.5 -0.9
B3_av384s 1.5 0.1
B3_av472s 2.7 0.2
B3_av476s 0.7 1.0
B3_av508s 2.1 0.6
B3_av520s 0.9 0.7
B3_av524s 1.5 0.6
B3_av556s 0.9 0.9
B3_av568s 0.7 1.9
B3_av600s 0.9 0.1
B3_av061s 0.4 -5.1
B3_av069s 0.7 -4.3
B3_av117s 1.6 -0.8
B3_av217s 1.8 -0.9
B3_av153s 2.5 -0.7
B3_av066s 2.1 -1.7
B3_av054s 2.0 -1.7
B3_av210s 1.3 -1.7
B3_av146s 1.3 -1.8
B3_av178s 1.4 -1.8
B3_av262s 0.7 -1.6
B3_av310s 1.1 -0.9
B3_av342s 1.6 -0.9
B3_av486s 1.3 -0.2
B3_av494s 1.4 -0.5
B3_av099s 2.1 -1.5
B3_av071s 5.7 -0.9
B3_av063s 3.4 -1.1
B3_av039s 1.5 -1.8
B3_av797s 2.1 -2.1
B3_av015s 2.8 -1.2
B3_av151s 1.6 -0.9
B3_av171s 1.8 -1.1
B3_av231s 2.8 -0.8
B3_av267s 1.7 -1.1
B3_av283s 6.6 -0.6
B3_av323s 1.9 -0.4
B3_av801s 1.0 -3.3
B3_av327s 0.4 0.9
B3_av663s 0.9 0.9
B3_av643s 0.6 -0.9
B3_av619s 0.3 3.5
B3_av575s 0.9 -0.5
B3_av559s 1.5 -0.6
B3_av671s 1.0 -0.5
B3_av805s 1.3 -2.6
B3_av108s 2.3 -0.3
B3_av080s 1.5 -0.7
B3_av164s 1.6 -1.0
B3_av192s 1.3 -0.8
B3_av256s 1.8 -0.7
B3_av208s 1.6 -0.5
B3_av296s 1.6 -0.8
B3_av336s 2.1 0.1
B3_av340s 1.9 0.0
B3_av352s 1.8 -0.2
B3_av548s 1.2 -0.3
B3_av564s 1.0 -0.5
B3_av592s 0.5 0.1
B3_av616s 0.6 1.1
B3_av129s 2.1 -1.9
B3_av137s 1.8 -1.7
B3_av073s 1.2 -1.5
B3_av177s 1.8 -1.6
B3_av249s 1.4 -1.2
B3_av008s 1.7 -1.3
B3_av098s 2.0 -1.4
B3_av218s 2.1 -0.8
B3_av258s 1.5 -1.2
B3_av154s 1.8 -0.9
B3_av414s 1.9 -0.6
B3_av430s 1.1 0.0
B3_av750s 2.0 -0.5
B3_av530s 1.1 -0.5
B3_av542s 1.2 -0.4
B3_av043s 1.4 -1.1
B3_av067s 1.3 -1.5
B3_av079s 1.3 -0.9
B3_av103s 1.6 -1.0
B3_av809s 1.4 -2.0
B3_av083s 1.5 -1.3
B3_av183s 1.6 -1.1
B3_av247s 1.3 -0.8
B3_av227s 1.7 -1.1
B3_av195s 1.6 -1.0
B3_av263s 1.1 -0.9
B3_av311s 1.3 -1.0
B3_av813s 1.9 -1.3
B3_av387s 2.1 -0.1
B3_av503s 1.5 -0.2
B3_av499s 0.8 -0.2
B3_av723s 0.6 0.1
B3_av651s 1.0 1.4
B3_av631s 1.4 0.0
B3_av615s 1.8 0.3
B3_av817s 1.9 -1.5
B3_av124s 1.6 -0.8
B3_av116s 1.5 -1.0
B3_av224s 1.2 -0.8
B3_av156s 1.6 -0.3
B3_av160s 1.1 -1.3
B3_av280s 1.2 -0.9
B3_av272s 1.8 -0.7
B3_av304s 1.4 0.1
B3_av348s 1.2 -0.9
B3_av396s 1.4 -0.5
B3_av468s 1.4 -0.4
B3_av488s 1.0 0.3
B3_av464s 1.5 -0.6
B3_av552s 1.2 0.7
B3_av560s 1.1 -0.2
B3_av700s 1.7 0.5
B3_av580s 1.4 -0.5
B3_av604s 2.0 0.6
B3_av105s 1.5 -1.1
B3_av053s 1.5 -1.7
B3_av113s 1.3 -1.8
B3_av145s 1.0 -1.7
B3_av022s 2.1 -1.2
B3_av050s 1.1 -1.7
B3_av158s 0.9 -1.9
B3_av186s 1.9 -0.9
B3_av190s 1.6 -1.4
B3_av274s 1.5 0.0
B3_av282s 1.6 -1.2
B3_av366s 1.6 0.0
B3_av534s 1.3 0.2
B3_av538s 2.0 0.0
B3_av031s 1.8 -1.2
B3_av011s 1.1 -1.1
B3_av009s 1.9 -1.0
B3_av047s 1.8 -1.4
B3_av821s 2.0 -1.7
B3_av219s 1.7 -0.5
B3_av163s 1.9 -1.1
B3_av243s 1.3 -1.3
B3_av295s 1.7 -0.8
B3_av335s 2.1 -0.2
B3_av825s 1.9 -1.7
B3_av379s 1.8 -0.8
B3_av431s 1.7 0.2
B3_av475s 1.6 0.5
B3_av523s 2.1 0.1
B3_av555s 2.2 -0.1
B3_av595s 0.6 0.3
B3_av120s 2.2 -0.5
B3_av829s 1.4 -1.7
B3_av092s 1.1 -1.2
B3_av152s 1.7 -0.5
B3_av172s 1.1 -0.9
B3_av228s 1.5 -1.0
B3_av260s 1.6 -0.9
B3_av308s 2.0 0.1
B3_av408s 0.6 0.2
B3_av452s 2.0 0.5
B3_av456s 1.2 0.0
B3_av584s 2.6 -0.5
B3_av608s 1.5 -0.6
B3_av624s 2.3 -0.2
B3_av640s 1.5 -0.4
B3_av656s 0.9 0.0
B3_av664s 0.8 1.7
B3_av085s 1.6 -1.5
B3_av093s 1.7 -1.2
B3_av193s 1.4 -1.6
B3_av014s 1.5 -1.3
B3_av090s 1.4 -1.5
B3_av182s 1.5 -1.2
B3_av242s 2.0 -1.2
B3_av338s 1.4 -0.6
B3_av394s 1.3 -0.8
B3_av378s 1.8 -1.0
B3_av035s 2.1 -1.4
B3_av095s 1.1 -1.3
B3_av115s 1.6 -1.1
B3_av833s 1.7 -1.7
B3_av331s 1.5 -0.7
B3_av367s 1.0 0.1
B3_av435s 1.4 -0.6
B3_av459s 1.7 -0.8
B3_av471s 1.8 -0.1
B3_av479s 1.4 -0.7
B3_av519s 2.4 0.2
B3_av571s 1.0 1.1
B3_av659s 1.7 -0.5
B3_av028s 1.7 -0.5
B3_av088s 2.0 -0.6
B3_av236s 2.2 -0.5
B3_av180s 2.5 -0.9
B3_av344s 1.4 -0.7
B3_av300s 1.5 -0.4
B3_av356s 2.0 0.0
B3_av376s 1.8 -0.8
B3_av065s 1.9 -1.7
B3_av708s 0.6 0.9
B3_av636s 1.9 0.4
B3_av576s 1.3 0.1
B3_av632s 0.8 1.0
B3_av109s 1.1 -2.0
B3_av121s 1.2 -1.8
B3_av169s 1.8 -1.5
B3_av023s 2.3 -0.9
B3_av391s 1.6 -0.5
B3_av443s 1.3 -0.3
B3_av423s 1.7 -0.7
B3_av383s 1.1 -0.3
B3_av699s 1.5 0.1
B3_av535s 1.1 0.5
B3_av483s 1.5 -0.6
B3_av495s 1.5 -0.4
B3_av487s 1.4 0.0
B3_av539s 2.0 0.4
B3_av507s 1.4 0.8
B3_av455s 1.3 -0.2
B3_av044s 1.5 -0.5
B3_av072s 1.9 -0.9
B3_av176s 2.3 -0.5
B3_av144s 1.6 -0.9
B3_av460s 1.6 -0.6
B3_av268s 1.8 -0.7
B3_av748s 1.1 0.7
B3_av644s 0.9 0.0

We might also look at this visually, with tracelines.

Distribution of discrimination and of difficulty

Items with discrimination less than 0.5

Items with low discrimination (less than 0.5).

## [1] "B3_ord86s" "B3_ord63s" "B3_ord71s" "B3_av528s" "B3_av077s" "B3_av789s"
## [7] "B3_av061s" "B3_av327s" "B3_av619s"

VOKABULAR

We have a total of 178 items. The number of observations per item:
item1 observation1 item2 observation2 item3 observation3
B3_vsf01s 797 B3_vsk015s 252 B3_vo029s 252
B3_vsf44s 786 B3_vsk013s 252 B3_vo030s 252
B3_vsf47s 532 B3_vsk014s 252 B3_vo031s 252
B3_vsf29s 984 B3_vsk016s 238 B3_vo071s 238
B3_vsf49s 532 B3_vsk017s 238 B3_vo074s 238
B3_vsf03s 532 B3_vsk018s 238 B3_vo076s 238
B3_vsf19s 786 B3_vo058s 428 B3_vo078s 238
B3_vsf18s 922 B3_vo001s 356 B3_vo079s 238
B3_vsf16s 790 B3_vo002s 356 B3_vo080s 238
B3_vsf08s 525 B3_vo003s 356 B3_vo081s 469
B3_vsf22s 525 B3_vo004s 356 B3_vo082s 238
B3_vsf41s 525 B3_vo005s 356 B3_vo083s 231
B3_vsf11s 525 B3_vo006s 356 B3_vo087s 231
B3_vsf13s 525 B3_vo007s 356 B3_vo088s 231
B3_vsf07s 779 B3_vo008s 356 B3_vo090s 231
B3_vsf42s 779 B3_vo009s 587 B3_vo092s 231
B3_vsf27s 254 B3_vo010s 420 B3_vo093s 231
B3_vsf35s 254 B3_vo011s 420 B3_vo094s 231
B3_vsf10s 254 B3_vo054s 353 B3_my501s 420
B3_vsf21s 706 B3_vo056s 425 B3_my502s 420
B3_vsf26s 655 B3_vo077s 591 B3_my601s 356
B3_vsf46s 265 B3_vo043s 353 B3_my603s 356
B3_vsf17s 265 B3_vo044s 353 B3_my605s 356
B3_vsf06s 265 B3_vo045s 353 B3_my622s 356
B3_vsf12s 265 B3_vo046s 353 B3_my504s 425
B3_vsf37s 597 B3_vo047s 353 B3_my602s 353
B3_vsf33s 452 B3_vo048s 353 B3_my604s 353
B3_vsf24s 452 B3_vo049s 353 B3_my606s 353
B3_vsf43s 452 B3_vo050s 353 B3_my623s 353
B3_vsf30s 452 B3_vo051s 353 B3_my505s 64
B3_vsf38s 452 B3_vo052s 353 B3_my507s 64
B3_vsf25s 805 B3_vo053s 353 B3_my607s 64
B3_vsf48s 390 B3_vo055s 425 B3_my612s 64
B3_vsf02s 390 B3_vo084s 64 B3_my614s 64
B3_vsf31s 743 B3_vo012s 64 B3_my627s 64
B3_vsf45s 743 B3_vo013s 64 B3_my506s 72
B3_vsf14s 722 B3_vo014s 64 B3_my508s 72
B3_vsf09s 722 B3_vo015s 64 B3_my608s 72
B3_vsf34s 353 B3_vo016s 64 B3_my615s 72
B3_vsf05s 353 B3_vo017s 64 B3_my616s 72
B3_vsf39s 353 B3_vo018s 64 B3_my503s 72
B3_vsf20s 353 B3_vo019s 64 B3_my509s 252
B3_vsf36s 353 B3_vo020s 64 B3_my510s 252
B3_vsf23s 332 B3_vo021s 316 B3_my609s 252
B3_vsf04s 332 B3_vo022s 316 B3_my617s 252
B3_vsf28s 332 B3_vo085s 303 B3_my618s 252
B3_vsf40s 332 B3_vo057s 72 B3_my629s 252
B3_vsf15s 332 B3_vo059s 72 B3_my511s 469
B3_vsk002s 356 B3_vo061s 72 B3_my512s 469
B3_vsk003s 356 B3_vo063s 72 B3_my610s 238
B3_vsk001s 587 B3_vo064s 72 B3_my611s 238
B3_vsk004s 584 B3_vo065s 72 B3_my613s 238
B3_vsk005s 353 B3_vo066s 72 B3_my619s 238
B3_vsk006s 353 B3_vo067s 72 B3_my515s 231
B3_vsk007s 64 B3_vo068s 310 B3_my516s 231
B3_vsk008s 64 B3_vo069s 72 B3_my620s 231
B3_vsk009s 64 B3_vo023s 252 B3_my621s 231
B3_vsk010s 72 B3_vo026s 252 B3_my626s 231
B3_vsk011s 303 B3_vo027s 252 NA NA
B3_vsk012s 72 B3_vo028s 252 NA NA

Level of difficulty

We have 178 dichotomous items, and 0 polytomous items. Here is the the distribution of percentage correct for the dichotomous items:

The items were never answered incorrectly, and are removed from further analysis.

Also, 1762 students did not receive any items from this category.

IRT

The resulting test information curve is as follows:

Item parameters a (discrimination) and d (difficulty)
a d
B3_vsf01s 1.0 -3.0
B3_vsf44s 0.9 -1.5
B3_vsf47s 1.2 -2.1
B3_vsf29s 1.1 -1.9
B3_vsf49s 1.1 -2.3
B3_vsf03s 0.9 -3.5
B3_vsf19s 0.9 -2.9
B3_vsf18s 0.9 -3.2
B3_vsf16s 0.9 -3.0
B3_vsf08s 0.7 -2.2
B3_vsf22s 0.8 -3.0
B3_vsf41s 1.1 -2.7
B3_vsf11s 0.8 -3.4
B3_vsf13s 0.9 -2.8
B3_vsf07s 0.9 -2.2
B3_vsf42s 1.1 -2.7
B3_vsf27s 1.6 -2.4
B3_vsf35s 1.2 -1.8
B3_vsf10s 0.7 -3.2
B3_vsf21s 1.2 -2.6
B3_vsf26s 0.9 -3.1
B3_vsf46s 1.9 -1.8
B3_vsf17s 0.9 -2.8
B3_vsf06s 0.7 -2.1
B3_vsf12s 0.6 -3.3
B3_vsf37s 0.8 -2.8
B3_vsf33s 1.2 -2.9
B3_vsf24s 0.8 -3.6
B3_vsf43s 0.7 -4.6
B3_vsf30s 0.8 -3.7
B3_vsf38s 1.2 -2.0
B3_vsf25s 0.8 -3.0
B3_vsf48s 0.9 -3.5
B3_vsf02s 1.3 -2.6
B3_vsf31s 0.9 -2.9
B3_vsf45s 1.4 -1.7
B3_vsf14s 1.6 -2.2
B3_vsf09s 0.6 -3.5
B3_vsf34s 1.2 -1.8
B3_vsf05s 1.1 -2.0
B3_vsf39s 1.9 -2.2
B3_vsf20s 1.3 -2.0
B3_vsf36s 1.1 -1.9
B3_vsf23s 1.3 -2.1
B3_vsf04s 0.8 -4.0
B3_vsf28s 0.9 -3.3
B3_vsf40s 1.4 -1.9
B3_vsf15s 0.8 -3.9
B3_vsk002s 1.6 -0.5
B3_vsk003s 1.5 -0.5
B3_vsk001s 1.2 -0.5
B3_vsk004s 0.8 0.3
B3_vsk005s 1.8 -0.2
B3_vsk006s 1.8 -0.8
B3_vsk007s 1.5 1.0
B3_vsk008s 0.9 0.1
B3_vsk009s 1.6 -1.2
B3_vsk010s 1.5 -1.3
B3_vsk011s 1.2 -0.8
B3_vsk012s 0.9 0.8
B3_vsk015s 0.8 0.1
B3_vsk013s 1.0 0.6
B3_vsk014s 0.8 0.9
B3_vsk016s 0.6 1.4
B3_vsk017s 1.2 -0.6
B3_vsk018s 0.8 0.4
B3_vo058s 0.8 0.2
B3_vo001s 0.6 1.5
B3_vo002s 0.9 0.1
B3_vo003s 1.4 -0.4
B3_vo004s 1.5 -0.2
B3_vo005s 1.3 -0.3
B3_vo006s 2.2 -0.8
B3_vo007s 1.6 0.1
B3_vo008s 1.7 -0.6
B3_vo009s 1.9 -0.5
B3_vo010s 1.7 -0.7
B3_vo011s 1.4 -0.1
B3_vo054s 2.1 -0.7
B3_vo056s 1.9 -0.4
B3_vo077s 0.9 0.5
B3_vo043s 1.2 0.2
B3_vo044s 1.1 0.3
B3_vo045s 2.3 -0.6
B3_vo046s 2.2 -0.5
B3_vo047s 1.3 -0.2
B3_vo048s 1.4 0.3
B3_vo049s 1.7 -0.5
B3_vo050s 1.5 0.2
B3_vo051s 1.9 -0.8
B3_vo052s 1.7 -0.3
B3_vo053s 1.7 -0.5
B3_vo055s 0.6 3.5
B3_vo084s 0.4 -2.1
B3_vo012s 0.9 0.0
B3_vo013s 1.3 -0.2
B3_vo014s 1.1 -0.1
B3_vo015s 1.3 0.4
B3_vo016s 1.2 -0.1
B3_vo017s 0.6 1.1
B3_vo018s 1.2 -0.1
B3_vo019s 1.8 0.6
B3_vo020s 1.8 -0.7
B3_vo021s 0.8 0.4
B3_vo022s 0.5 2.6
B3_vo085s 1.4 -1.0
B3_vo057s 0.9 0.2
B3_vo059s 0.7 0.4
B3_vo061s 0.6 2.4
B3_vo063s 2.1 -1.0
B3_vo064s 2.0 -0.5
B3_vo065s 1.9 -1.4
B3_vo066s 0.9 0.7
B3_vo067s 0.7 -0.4
B3_vo068s 0.6 0.5
B3_vo069s 1.5 0.5
B3_vo023s 0.8 1.5
B3_vo026s 1.5 -0.1
B3_vo027s 2.5 -0.7
B3_vo028s 2.1 -0.8
B3_vo029s 1.2 0.3
B3_vo030s 0.9 -0.2
B3_vo031s 0.3 2.9
B3_vo071s 1.2 0.9
B3_vo074s 0.7 -1.1
B3_vo076s 1.2 -1.2
B3_vo078s 1.3 -1.7
B3_vo079s 0.8 2.2
B3_vo080s 1.1 0.9
B3_vo081s 0.6 1.1
B3_vo082s 0.9 -0.6
B3_vo083s 1.2 -0.5
B3_vo087s 1.5 -0.4
B3_vo088s 0.8 -0.4
B3_vo090s 0.5 1.7
B3_vo092s 0.7 0.9
B3_vo093s 1.1 0.0
B3_vo094s 1.4 -0.5
B3_my501s 1.0 -2.1
B3_my502s 1.0 -2.7
B3_my601s 0.6 -1.2
B3_my603s 1.1 -1.7
B3_my605s 1.0 -1.5
B3_my622s 0.8 -1.7
B3_my504s 0.7 -1.7
B3_my602s 0.9 -2.2
B3_my604s 0.8 -1.0
B3_my606s 1.0 -1.9
B3_my623s 0.9 -2.2
B3_my505s 0.8 0.4
B3_my507s 2.1 -1.1
B3_my607s 1.4 -1.9
B3_my612s 1.7 -1.3
B3_my614s 1.8 -1.9
B3_my627s 0.9 -1.8
B3_my506s 0.7 -0.2
B3_my508s 0.1 -20.4
B3_my608s 0.8 -1.9
B3_my615s 1.0 -3.1
B3_my616s 0.7 -2.8
B3_my503s 1.5 -2.4
B3_my509s 1.1 -2.2
B3_my510s 0.7 -2.0
B3_my609s 0.5 -1.7
B3_my617s 0.8 -0.3
B3_my618s 1.2 -2.6
B3_my629s 1.4 -1.2
B3_my511s 1.0 0.1
B3_my512s 0.8 1.3
B3_my610s 0.9 -1.7
B3_my611s 1.0 -0.9
B3_my613s 0.7 -3.6
B3_my619s 0.9 -1.5
B3_my515s 0.8 -2.9
B3_my516s 0.5 -0.4
B3_my620s 0.7 -3.0
B3_my621s 0.7 -3.6
B3_my626s 0.7 -2.0

We might also look at this visually, with tracelines.

Distribution of discrimination and of difficulty

Items with discrimination less than 0.5

Items with low discrimination (less than 0.5).

## [1] "B3_vo084s" "B3_vo031s" "B3_my508s"

LESING

We have a total of 122 items. The number of observations per item:
item1 observation1 item2 observation2 item3 observation3
B3_lf002s 532 B3_lf055s 597 B3_sl0704s 1139
B3_lf003s 532 B3_lf057s 265 B3_sl122s 786
B3_lf072s 532 B3_lf059s 265 B3_sl232s 786
B3_lf073s 532 B3_lf053s 265 B3_sl262s 786
B3_lf044s 532 B3_lf069s 784 B3_sl0201s 786
B3_lf045s 532 B3_lf070s 784 B3_sl271s 790
B3_lf046s 532 B3_lf006s 452 B3_sl0203s 525
B3_lf047s 532 B3_lf007s 452 B3_sl1701s 525
B3_lf048s 532 B3_lf008s 452 B3_sl0503s 857
B3_lf060s 786 B3_lf009s 452 B3_sl162s 525
B3_lf061s 786 B3_lf010s 452 B3_sl241s 525
B3_lf062s 786 B3_lf011s 452 B3_sl281s 265
B3_lf051s 878 B3_lf079s 452 B3_sl0301s 655
B3_lf052s 878 B3_lf080s 452 B3_sl0701s 265
B3_lf066s 915 B3_lf001s 784 B3_sl2001s 265
B3_lf067s 915 B3_lf029s 390 B3_sl173s 265
B3_lf068s 915 B3_lf030s 390 B3_sl242s 265
B3_lf017s 525 B3_lf031s 390 B3_sl0702s 452
B3_lf018s 525 B3_lf032s 390 B3_sl1801s 452
B3_lf019s 525 B3_lf033s 390 B3_sl0604s 452
B3_lf020s 525 B3_lf034s 390 B3_sl182s 452
B3_lf021s 525 B3_lf035s 390 B3_sl243s 452
B3_lf022s 525 B3_lf036s 390 B3_sl291s 805
B3_lf004s 254 B3_lf037s 390 B3_sl0401s 452
B3_lf005s 254 B3_lf012s 353 B3_sl0703s 390
B3_lf074s 254 B3_lf013s 353 B3_sl2301s 390
B3_lf075s 254 B3_lf014s 353 B3_sl183s 390
B3_lf076s 254 B3_lf015s 353 B3_sl251s 390
B3_lf077s 254 B3_lf016s 353 B3_sl301s 722
B3_lf078s 254 B3_lf063s 353 B3_sl0501s 390
B3_lf065s 254 B3_lf064s 353 B3_sl0502s 353
B3_lf071s 254 B3_lf038s 332 B3_sl202s 353
B3_lf049s 618 B3_lf039s 332 B3_sl252s 353
B3_lf050s 618 B3_lf040s 332 B3_sl302s 353
B3_lf023s 265 B3_lf041s 332 B3_sl321s 353
B3_lf024s 265 B3_lf042s 332 B3_sl0801s 332
B3_lf025s 265 B3_lf043s 332 B3_sl212s 332
B3_lf026s 265 B3_lf056s 332 B3_sl261s 332
B3_lf027s 265 B3_lf058s 332 B3_sl311s 332
B3_lf028s 265 B3_sl0601s 786 B3_sl331s 332
B3_lf054s 597 B3_sl0803s 786 NA NA

Level of difficulty

We have 122 dichotomous items, and 0 polytomous items. Here is the the distribution of percentage correct for the dichotomous items:

The items were never answered incorrectly, and are removed from further analysis.

Also, 1762 students did not receive any items from this category.

IRT

The resulting test information curve is as follows:

Item parameters a (discrimination) and d (difficulty)
a d
B3_lf002s 1.4 -1.1
B3_lf003s 1.2 -0.7
B3_lf072s 1.0 -1.6
B3_lf073s 1.2 -1.3
B3_lf044s 1.9 -0.1
B3_lf045s 1.9 -0.3
B3_lf046s 1.3 0.3
B3_lf047s 1.9 0.0
B3_lf048s 0.8 1.9
B3_lf060s 1.0 -0.2
B3_lf061s 1.3 -0.1
B3_lf062s 1.3 -0.2
B3_lf051s 1.0 0.1
B3_lf052s 1.0 0.0
B3_lf066s 1.1 0.3
B3_lf067s 1.2 -0.3
B3_lf068s 1.3 0.0
B3_lf017s 1.9 -0.1
B3_lf018s 2.1 -0.2
B3_lf019s 2.4 -0.3
B3_lf020s 2.4 -0.4
B3_lf021s 1.6 -0.3
B3_lf022s 1.6 -0.2
B3_lf004s 2.1 -0.3
B3_lf005s 0.5 1.3
B3_lf074s 1.8 -0.3
B3_lf075s 0.5 0.6
B3_lf076s 2.3 -0.5
B3_lf077s 1.2 0.4
B3_lf078s 1.0 0.6
B3_lf065s 1.9 0.0
B3_lf071s 0.4 0.9
B3_lf049s 0.7 0.3
B3_lf050s 1.0 0.3
B3_lf023s 1.6 0.0
B3_lf024s 1.6 0.3
B3_lf025s 2.4 0.1
B3_lf026s 2.2 -0.1
B3_lf027s 1.3 -0.2
B3_lf028s 1.8 0.2
B3_lf054s 1.5 -0.5
B3_lf055s 1.9 -0.2
B3_lf057s 1.2 0.2
B3_lf059s 1.7 -0.2
B3_lf053s 1.4 -0.2
B3_lf069s 0.6 0.2
B3_lf070s 1.0 0.0
B3_lf006s 1.1 0.2
B3_lf007s 0.6 1.0
B3_lf008s 1.7 0.2
B3_lf009s 1.2 0.6
B3_lf010s 1.6 0.1
B3_lf011s 1.1 0.5
B3_lf079s 1.4 -1.2
B3_lf080s 1.0 -0.8
B3_lf001s 1.1 -0.4
B3_lf029s 0.9 -0.4
B3_lf030s 1.3 0.2
B3_lf031s 1.9 0.3
B3_lf032s 1.3 -0.3
B3_lf033s 1.4 0.2
B3_lf034s 2.2 -0.2
B3_lf035s 2.0 -0.3
B3_lf036s 2.0 0.0
B3_lf037s 0.7 0.8
B3_lf012s 1.5 -0.7
B3_lf013s 1.4 -0.6
B3_lf014s 1.7 -0.2
B3_lf015s 1.5 -0.2
B3_lf016s 1.1 0.3
B3_lf063s 0.9 -0.3
B3_lf064s 0.9 -0.1
B3_lf038s 1.4 0.1
B3_lf039s 1.3 0.7
B3_lf040s 1.6 0.0
B3_lf041s 1.9 0.0
B3_lf042s 1.6 -0.2
B3_lf043s 1.7 0.2
B3_lf056s 0.8 -0.2
B3_lf058s 0.7 2.0
B3_sl0601s 0.9 -1.9
B3_sl0803s 1.1 -0.9
B3_sl0704s 1.9 -1.0
B3_sl122s 1.1 -1.4
B3_sl232s 1.1 -1.1
B3_sl262s 1.4 -1.3
B3_sl0201s 1.2 0.5
B3_sl271s 1.3 -1.5
B3_sl0203s 1.3 -1.0
B3_sl1701s 1.4 -0.9
B3_sl0503s 1.5 -1.0
B3_sl162s 1.7 -1.3
B3_sl241s 1.6 -1.6
B3_sl281s 0.7 -0.7
B3_sl0301s 1.2 -0.9
B3_sl0701s 1.0 -1.0
B3_sl2001s 1.0 -1.1
B3_sl173s 1.0 -0.9
B3_sl242s 1.3 -1.8
B3_sl0702s 1.1 -1.7
B3_sl1801s 1.3 -0.8
B3_sl0604s 1.2 -1.0
B3_sl182s 1.0 -1.4
B3_sl243s 1.5 -1.1
B3_sl291s 1.8 -0.9
B3_sl0401s 1.8 -0.9
B3_sl0703s 1.3 -1.3
B3_sl2301s 1.6 -1.3
B3_sl183s 1.0 -1.2
B3_sl251s 0.4 0.2
B3_sl301s 1.5 -1.4
B3_sl0501s 0.9 -1.4
B3_sl0502s 1.6 -0.8
B3_sl202s 2.0 -1.1
B3_sl252s 1.6 -1.0
B3_sl302s 1.1 -1.1
B3_sl321s 2.1 -0.9
B3_sl0801s 1.4 -1.2
B3_sl212s 1.5 -1.4
B3_sl261s 1.4 -1.2
B3_sl311s 1.2 -1.3
B3_sl331s 1.2 -0.7

We might also look at this visually, with tracelines.

Distribution of discrimination and of difficulty

Items with discrimination less than 0.5

Items with low discrimination (less than 0.5).

## [1] "B3_lf075s" "B3_lf071s" "B3_sl251s"

STAVING

We have a total of 56 items. The number of observations per item:
item1 observation1 item2 observation2 item3 observation3
B3_st140s 504 B3_st152s 246 B3_st147s 722
B3_st101s 760 B3_st151s 239 B3_st145s 390
B3_st102s 505 B3_st134s 245 B3_st142s 390
B3_st103s 502 B3_st115s 254 B3_st123s 390
B3_st160s 504 B3_st159s 246 B3_st148s 390
B3_st155s 504 B3_st116s 246 B3_st128s 390
B3_st117s 497 B3_st122s 242 B3_st157s 338
B3_st110s 493 B3_st112s 242 B3_st162s 331
B3_st141s 749 B3_st114s 243 B3_st144s 338
B3_st105s 752 B3_st153s 428 B3_st129s 336
B3_st106s 492 B3_st154s 763 B3_st126s 335
B3_st136s 490 B3_st149s 773 B3_st121s 338
B3_st150s 486 B3_st124s 437 B3_st131s 337
B3_st125s 477 B3_st138s 426 B3_st119s 327
B3_st161s 476 B3_st133s 424 B3_st139s 323
B3_st113s 468 B3_st130s 426 B3_st146s 321
B3_st107s 247 B3_st132s 423 B3_st120s 318
B3_st108s 688 B3_st118s 712 B3_st135s 332
B3_st111s 248 B3_st156s 722 NA NA

Level of difficulty

We have 50 dichotomous items, and 0 polytomous items. Here is the the distribution of percentage correct for the dichotomous items:

The items were never answered incorrectly, and are removed from further analysis.

Also, 1762 students did not receive any items from this category.

IRT

Troublesome items! Initial IRT resulted in negative discriminatin for item B3_st101s and very low for B3_st149s which where removed prior to IRT. Also, B3_st156s had very high discrimination (44) and was removed. The resulting test information curve is as follows:

Item parameters a (discrimination) and d (difficulty)
a d
B3_st140s 1.0 -2.6
B3_st102s 1.2 -2.8
B3_st103s 0.3 -6.5
B3_st160s 1.0 -0.9
B3_st155s 1.7 0.2
B3_st117s 1.8 0.1
B3_st110s 1.2 -0.1
B3_st141s 1.2 -1.2
B3_st105s 0.9 -1.1
B3_st106s 1.3 -0.9
B3_st136s 1.2 -0.4
B3_st150s 1.1 -2.4
B3_st125s 1.1 1.2
B3_st161s 2.1 1.2
B3_st113s 1.8 -1.2
B3_st107s 1.9 -1.5
B3_st108s 1.4 -2.5
B3_st111s 1.3 -0.6
B3_st152s 1.4 0.8
B3_st151s 2.0 -1.8
B3_st134s 1.4 -3.7
B3_st115s 1.6 -1.5
B3_st159s 1.7 -1.7
B3_st116s 1.9 0.8
B3_st122s 2.7 0.9
B3_st112s 1.2 2.5
B3_st114s 2.1 0.4
B3_st153s 1.2 -3.2
B3_st154s 0.7 -2.7
B3_st124s 1.1 -2.1
B3_st138s 2.4 0.5
B3_st133s 2.4 1.2
B3_st130s 2.6 0.4
B3_st132s 1.9 1.1
B3_st118s 3.5 1.3
B3_st147s 1.8 0.2
B3_st157s 0.4 -2.4
B3_st162s 2.7 0.6
B3_st144s 0.9 0.2
B3_st129s 2.0 1.0
B3_st126s 2.0 0.6
B3_st121s 2.5 0.7
B3_st131s 3.0 0.3
B3_st119s 1.5 -0.4
B3_st139s 1.5 -0.2
B3_st146s 2.3 1.1
B3_st120s 2.1 0.6

We might also look at this visually, with tracelines.

Distribution of discrimination and of difficulty

Items with discrimination less than 0.5

Items with low discrimination (less than 0.5).

## [1] "B3_st103s" "B3_st157s"

NB: These must be removed!! and analysis is re-run