The Use of Loglinear Models for Assessing Differential Item Functioning Across Manifest and Latent Examinee Groups

Loglinear latent class models are used to detect differential item functioning (DIF). These models are formulated in such a manner that the attribute to be assessed may be continuous, as in a Rasch model, or categorical, as in Latent Class Mastery models. Further, an item may exhibit DIF with respect to a manifest grouping variable, a latent grouping variable, or both. Likelihood-ratio tests for assessing the presence of various types of DIF are described, and these methods are illustrated through the analysis of a "real world" data set

Multimode waveguides of Photodefinable epoxy for optical backplane applications

We developed photodefined, multimode-fiber compatible waveguides based on epoxies. These waveguides will be embedded in backplane PCB’s for optical interconnect applications using 850 nm VCSELs as light sources. Apart from very low loss, the material selection took into account, PCB compatibility and low yellowing due to high temperature processing (for PCB lamination and soldering). The waveguides showed losses < 0.06 dB/cm at 832 nm and 633 nm. Their loss increase after aging (1 hr at 185 °C) was limited to 0.04 dB/cm at 850 nm. Waveguides realized on FR-4 (epoxyfiberglass)PCB material are demonstrated

Item bias detection using the loglinear Rasch model:Observed and unobserved subgroups

A method is proposed for the detection of item bias with respect to observed or unobserved subgroups. The method uses quasi-loglinear models for the incomplete subgroup x test score x item 1 x ... x item k contingency table. If the subgroup membership is unknown, the models are the incomplete-latent-class models of S. J. Haberman (1979). The (conditional) Rasch model is formulated as a quasi-loglinear model. The parameters in this model that correspond to the main effects of the item responses are the conditional estimates of the parameters in the Rasch model. Item bias can then be tested by comparing the quasi-loglinear-Rasch model with models that contain parameters for the interaction of item responses and the subgroups. An example uses data from a test taken by 286 Dutch undergraduates who took a multiplication test using Roman numerals and numbers written out in Dutch. Some of the examinees had received training in multiplying Roman numerals. It was expected that Roman items would be biased, and the procedure confirmed this bias. Five tables present the models and study data

Measurement exchangeability and normal one-factor models

The one-factor model restricts the covariance structure of the observed variables on the basis of assumptions about their relationship with an unobserved variable. It is hard to justify these assumptions on substantive or empirical grounds. In this paper, alternative measurement models are proposed that are based on exchangeability of variables after admissible scale transformations. They provide an alternative interpretation of the model and do not involve unobserved variables. They also yield a new one-factor model for sum scales. © 2004 Biometrika Trust

Na’hjeNing’e’s Rivers Indigenous Maps, Diplomacy, and the Writing of Ioway Space

This essay examines an indigenous map (1837) of the Missouri and Mississippi river valleys, which offers an alternative to the territorial mappings of US empire in the era of Indian removal. The map was presented by the Ioway delegate Na’hjeNing’e during an intertribal treaty council in Washington in 1837 and depicts the Ioway Nation’s historical occupation of large areas in the Mississippi River Valley. Although the American treaty commissioners ultimately dismissed the map\u27s historical argument and the Ioway\u27s claims, its visual presentation of rivers and indigenous migrations routes marked an alternative to US territorial mappings of Indian country. Understanding the Mississippi River Valley as a site of territorial contestation, Na’hjeNing’e’s visual rhetoric took Ioway migrations along these waterways seriously as a basis for indigenous land claims and sovereignty, presenting an alternative to the settler state’s mappings of Native space. At the same time, the imbalance of power relations within American bureaucratic networks meant that the map is an example of disrespected literature: a form of indigenous writing that was legible within colonial settings, but nevertheless disregarded because it did not align with settler-colonial projects of indigenous dispossession. By considering the diplomatic calculations behind it, this essay argues that Na’hjeNing’e’s map asserted a representation of Ioway sovereignty, but also reveals the bounds on that sovereignty at a moment when removal policy and settler expansion profoundly reshaped the social and political place of Indian nations in North America

Na’hjeNing’e’s Rivers Indigenous Maps, Diplomacy, and the Writing of Ioway Space

This essay examines an indigenous map (1837) of the Missouri andMississippi river valleys, which offers an alternative to the territorial mappings of USempire in the era of Indian removal. The map was presented by the Ioway delegateNa’hje Ning’e during an intertribal treaty council in Washington in 1837 and depictsthe Ioway Nation’s historical occupation of large areas in the Mississippi River Valley.Although the American treaty commissioners ultimately dismissed the map's historicalargument and the Ioway's claims, its visual presentation of rivers and indigenousmigrations routes marked an alternative to US territorial mappings of Indian country.Understanding the Mississippi River Valley as a site of territorial contestation,Na’hjeNing’e’s visual rhetoric took Ioway migrations along these waterways seriouslyas a basis for indigenous land claims and sovereignty, presenting an alternative to thesettler state’s mappings of Native space. At the same time, the imbalance of powerrelations within American bureaucratic networks meant that the map is an example ofdisrespected literature: a form of indigenous writing that was legible within colonialsettings, but nevertheless disregarded because it did not align with settler-colonialprojects of indigenous dispossession. By considering the diplomatic calculationsbehind it, this essay argues that Na’hjeNing’e’s map asserted a representation of Iowaysovereignty, but also reveals the bounds on that sovereignty at a moment whenremoval policy and settler expansion profoundly reshaped the social and politicalplace of Indian nations in North America.This essay examines an indigenous map (1837) of the Missouri andMississippi river valleys, which offers an alternative to the territorial mappings of USempire in the era of Indian removal. The map was presented by the Ioway delegateNa’hje Ning’e during an intertribal treaty council in Washington in 1837 and depictsthe Ioway Nation’s historical occupation of large areas in the Mississippi River Valley.Although the American treaty commissioners ultimately dismissed the map's historicalargument and the Ioway's claims, its visual presentation of rivers and indigenousmigrations routes marked an alternative to US territorial mappings of Indian country.Understanding the Mississippi River Valley as a site of territorial contestation,Na’hjeNing’e’s visual rhetoric took Ioway migrations along these waterways seriouslyas a basis for indigenous land claims and sovereignty, presenting an alternative to thesettler state’s mappings of Native space. At the same time, the imbalance of powerrelations within American bureaucratic networks meant that the map is an example ofdisrespected literature: a form of indigenous writing that was legible within colonialsettings, but nevertheless disregarded because it did not align with settler-colonialprojects of indigenous dispossession. By considering the diplomatic calculationsbehind it, this essay argues that Na’hjeNing’e’s map asserted a representation of Iowaysovereignty, but also reveals the bounds on that sovereignty at a moment whenremoval policy and settler expansion profoundly reshaped the social and politicalplace of Indian nations in North America

Using a sprinkler infiltrometer and the GAML model to predict moving sprinkler performance in the field

The Green-Ampt (1911) equation has been regarded as one of the foremost infiltration models. Mein and Larson’s (1971) work extended its use to modelling infiltration under rainfall conditions, known as the GAML model, and Chu (1987) further extended its use to time-varying application rates such as occurs under moving sprinkler systems. However, Chu only demonstrated the efficacy of his work using simple, idealised application patterns that are not seen in the real world. This project, then, sought to extend Chu’s work by testing it in the field using real sprinkler performance data. Sprinkler performance data, using Nelson brand centre-pivot S3000 sprinkler heads, was collected for the project in the hydraulics laboratory at USQ, Toowoomba. A sprinkler infiltrometer was used in the field to determine modified GAML model parameters, per Chu (1986). A computer program written in Matlab, based on the graphical methods of Chu (1987), used the laboratory sprinkler data and the modified GAML parameters to make a prediction of the runoff that would be generated from a specified time-varying application rate. A mobile sprinkler rig was constructed to deliver the time-varying application rate of water in the field. A new concept for a sprinkler infiltrometer was tested in the course of the project. Initial work in the laboratory appeared promising but the concept failed to meet expectations in the field, principally due to wind interference. Consequently a small droplet-forming sprinkler infiltrometer was constructed and used for all of the field testing. The process of determining the modified GAML model parameters was reasonably successful. However, predictions of runoff by the computer model were consistently far larger than that measured. This was believed to be for two key reasons. Firstly, whilst Chu’s (1987) method worked well for simple application patterns, it appeared to struggle with real data and so the predicted runoff by the computer program could only be regarded with suspicion. Secondly, there were significant difficulties collecting all of the runoff from the soil plots in the field. These two reasons for the disparity between predicted and measured runoff meant that this project was not able to conclusively affirm or reject Chu’s (1987) method for applying the GAML model as being suitable for use with real moving sprinkler systems in the field

Rock Island Revisited: Black Hawk’s Life, Keokuk’s Oratory, and the Critique of US Indian Policy

This article examines the writings and oratory of the Sauk tribal leaders Keokuk and Black Hawk in the context of Indian diplomacy at Rock Island Indian agency. While Black Hawk\u27s autobiography Life of Mà-ka-tai-me-she-kià-kiàk (1833) is widely read today, Keokuk\u27s oratory has typically been dismissed as an accommodationist extension of US governmental discourses, as op-posed to Black Hawk\u27s rhetoric of resistance and criticism of the Black Hawk War. Complicating these historical narratives, this article argues that both Black Hawk and Keokuk produced collaborative publications that in similar ways critiqued the management of Indian affairs within networks of Indian agents, traders, and tribal leaders. Black Hawk\u27s Life challenges the legitimacy of Keokuk\u27s leadership within these networks, but also mounts a more structural critique of the bad management of Indian affairs at Rock Island Indian Agency. Keokuk\u27s oratory similar-ly addressed the economic and intertribal ramifications of American expansion, while also imagining that the agency of tribal leaders within the Indian Office held a potential to reassert an economic and social place for the Sauk Nation and the closely allied Meskwaki Nation. Operating through the technologies of the Indian Office, Black Hawk and Keokuk\u27s writing and oratory represent critical instances of institutional negotiation and intervention. Seen together, their oral, scribal, and print publications register the historical dynamics of removal in the Midwest, as it was elaborated and contested at the Rock Island Indian agency