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Table 4 Average Rasch difficulty estimates for the CTSR items by tier and content

From: Is it harder to know or to reason? Analyzing two-tier science assessment items using the Rasch measurement model

Content Tier 1 Tier 2 Average by Content
Control of Variables −1.23 −1.22 −1.22
Combinatorial Reasoning −0.16 0.02 −0.07
Probabilistic Reasoning −3.08 −3.32 −3.20
Proportional Reasoning 0.57 −0.40 0.08
Average by Tier −0.88 −1.02  
Model Fit statistics: AIC AICc BIC
12558.08 12572.13 12820.07
  1. Note. All measurement models were estimated as dichotomous Rasch models. The reported model fit statistics of AIC, AICc, and BIC are used to select this statistical model over others (not reported in this table). This model is the 60 parameter model