Let's build a library of standard datasets and their Rasch estimates. These can be used to confirm that Rasch software is functioning correctly and also for teaching about Rasch estimation.
Estimation method:
AMLE = Anchored Maximum Likelihood Estimation (MLE for estimating person abilities with known item difficulties)
CMLE = Conditional Maximum Likelihood Estimation (R- eRm, WINMIRA)
JMLE = Joint Maximum Likelihood Estimation (R-mixRasch, Winsteps) - no correction for estimation bias
MMLE = Marginal Maximum Likelihood Estimation (R-ltm, ConQuest)
PMLE = Pairwise Maximum Likelihood Estimation (R-pairwise, RUMM2030)
WMLE = Warm's Mean Likelihood Estimation (applied to MLE estimates)
All estimates are in logits. The estimate for column 1 (item 1) is set to 0.0 logits.
Standard dataset 1:
Complete dichotomous dataset of 2 columns (items) and 2 rows (persons):
0,1
1,0
All Rasch estimation methods: column estimates: 0.0, 0.0 ; row estimates: 0.0, 0.0.
Standard dataset 2:
Complete dichotomous dataset of 2 columns (items) and 3 rows (persons):
0,1
1,0
0,1
CMLE column estimates: 0.00000, -0.69315
AMLE row estimates: -0.34658, -0.34658, -0.34658
JMLE column estimates: 0.00000, -1.38629
JMLE row estimates: -0.69315, -0.69315, -0.69315
MMLE column estimates: 0.00000, -1.38629
AMLE row estimates: -0.69315, -0.69315, -0.69315
PMLE column estimates: 0.00000, -0.69315
AMLE row estimates: -0.34658, -0.34658, -0.34658
Standard dataset 3:
Complete dichotomous dataset of 3 columns (items) and 3 rows (persons):
1,0,0
0,1,1
0,1,1
CMLE column estimates: 0.00000, -1.00505, -1.00505
AMLE row estimates: -1.40449, 0.05635, 0.05635
WMLE row estimates: -1.17098, -0.18498, -0.18498
JMLE column estimates: 0.00000, -1.56593, -1.56593
JMLE row estimates: -1.84142, -0.27549, -0.27549
WMLE row estimates: -1.63506, -0.50850, -0.50850
MMLE column estimates: 0.00000, -1.38629, -1.38629
AMLE row estimates: -1.69820, -0.17070, -0.17070
WMLE row estimates: -1.48169, -0.40644, -0.40644
PMLE column estimates: 0.00000, -0.69315, -0.69315
AMLE row estimates: -1.17436, 0.24746, 0.24746
WMLE row estimates: -0.93166, 0.00210, 0.00210
Standard Dataset 4: Rating Scale
8 persons (rows) respond to 8 items (columns) on a 0-3 rating scale:
10000000 00210203 02001113 01012123 00122033 02110333 00123333 03333332 | or |
1,0,0,0,0,0,0,0 0,0,2,1,0,2,0,3 0,2,0,0,1,1,1,3 0,1,0,1,2,1,2,3 0,0,1,2,2,0,3,3 0,2,1,1,0,3,3,3 0,0,1,2,3,3,3,3 0,3,3,3,3,3,3,2 |
---|
The row (column) totals are 1, 8, 8, 10, 11, 13, 15, 20
This data matrix is symmetric. In principle, person (row) and item (column) standard deviations (S.D.) are the same.
Rasch logit estimates: Andrich Rating Scale Model, "Restricted" Model | |||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Estimation method | Software | Item difficulties = Columns | Person abilities (thetas)= Rows | Andrich Thresholds | Analyst | ||||||||||
Mean | Popn. S.D. | Sample S.D. | Mean | Popn. S.D. | Sample S.D. | 1 | 2 | 3 | |||||||
JMLE | Winsteps | .00 | 1.33 | 1.42 | -.39 | 1.33 | 1.42 | -.39 | .14 | .25 | J.M. Linacre | ||||
JMLE | jMetrik | .00 | 1.3793 | -.3831 | 1.3801 | -.35 | .14 | .21 | Dr. Bill Plummer Priyanka | ||||||
JMLE | mixRasch (R) | .00 | 1.382 | -.3837 | 1.3821 | -.35 | .14 | .21 | Vernon Mogol | ||||||
Standard Dataset 5: The LSAT Dichotomous Data
1000 persons (rows) respond to 5 items (columns) scored 0-1:
The data matrix is here.
No estimates received yet.
Comments, corrections and suggestions for more standard datasets are welcome.
John Michael Linacre
mike \at/ winsteps.com
Rasch Estimates for Standard Datasets. Linacre JM. Rasch Measurement Transactions, 2014, 28:1 p. 1453-4
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