Article Information

Hinemoa Elder^1*

¹Te Whatu Ora, Health NZ, Karol Czuba, Hiwai Hauora Raukawa Charitable Trust, Paula Kersten, independent researcher, Alfonso Caracuel, University of Granada, Kathryn M McPherson, AUT University.

^*Corresponding Author: Hinemoa Elder, FRANZCP, PhD, MNZM. Te Whatu Ora, Health NZ.

Received: 10 April 2024; Accepted: 18 April 2024; Published: 07 May 2024

Citation: Hinemoa Elder, Karol Czuba, Paula Kersten, Alfonso Caracuel, Kathryn McPherson. Te Waka Kuaka, Rasch Analysis of a Cultural Assessment Tool in Traumatic Brain Injury in Māori. Journal of Psychiatry and Psychiatric Disorders. 8 (2024): 101-110.

Abstract

Keywords

Traumatic brain injury, Māori, Rasch analysis, Measurement.

Article Details

1. Introduction

Traumatic Brain Injury (TBI) in Maori is a significant health problem. Population data shows that Maori youth are three times more likely to sustain clinically significant TBI compared to non-Maori [1]. A complicating factor in responding to Maori with TBI has been the lack understanding of the cultural importance of injury to the brain and head given the primacy placed on the head in Maori culture. For example, ‘he tapu te upoko’ is a well-known saying from Te Ao Maori (the Maori world) which means, the head is sacred. This statement clearly indicates the importance of brain injury from a cultural perspective [2].

Recent work has explored these concepts and developed a Maori theory and praxis of TBI [3, 4]. The research found that the concepts of wa (time), wahi (place), tangata (people) and wairua practices (activities that strengthen the unique connection between Maori people and the universe) were central to Maori in navigating recovery. Indeed, how much time is taken, where assessment and treatment takes place, who is present at assessments, and what culturally salient activities are embedded in these assessments and treatment are well understood by practitioners as critical to the engagement of Maori whanau, although formal research in these areas has not been conducted. Practice based evidence also shows that without these factors being implemented Maori whanau disengage from services and therefore do not have access to rehabilitation interventions leading to compromised outcomes. The issue of making time in assessment of Maori has recently been identified as vital to ensuring cultural practices are undertaken and therefore more accurate assessment and recommendations provided [5].

These aspects of comprehensive assessment of Maori may be in tension with clinical imperatives that emphasise efficiencies of time and prioritise brevity of assessment and treatment. While some needs of patients and relatives after a TBI are held trans-culturally, others depend on the specific social and cultural context in which people live. As tools for the assessment of these needs are influenced by culture, measures adapted from other cultures have shown substantial differences between countries, even if they share historical roots and language [6]. Despite some, albeit variable, awareness by health practitioners and researchers of these cultural issues [7, 8] no measures have been developed that might help to conceptualize the magnitude and nature of the cultural needs associated with Maori TBI. Such measures should enable tailored responses to these needs and thereby improve recovery outcomes, improve communication between whanau and clinicians and therefore improve the quality of assessments. The lack of such measures means that Maori cultural needs in the context of TBI lack recognition and attention, or if there is some awareness of these on the part of clinicians the approach is not systematically provided or monitored [9].

Measures used to monitor recovery and needs post-TBI, such as neuropsychological tests, have been developed elsewhere and Maori cultural norms and validation in the Maori community have not been carried out although such work is now underway in the context of the ageing brain [10]. This issue is well recognized as contributing to difficulties in interpreting scores for Maori [11]. Experts in cross-cultural neuropsychology warn that adaptations of tools across cultures has serious drawbacks affecting all stages of the assessment: review of records; interviews; neuropsychological testing; and interpretation of results [12]. Having measures developed by Maori for Maori is therefore a critical issue in ensuring cultural validity. Indeed, there continues to be some debate about what can be measured and how this could occur in a culturally authentic way given the experience of historical measures being used as a means of cultural marginalization of Maori [13]. Developing such measures aligns with the Patient Reported Outcome Measures (PROM) literature that recognizes these measures as a central component to improving multiple facets of care and support, raising the quality of outcomes from illness and injury including in TBI[14, 15]. The need for a dual-purpose tool which serves to assess both cultural needs and also measure outcomes with cultural salience for Maori was apparent from clinical experience, and is frequently requested by Maori whanau seeking tools they felt reflected their realities. The lack of such measures in the literature indicated this was a significant gap to be addressed. This study aimed to examine the internal construct validity using Rasch analysis of a Maori cultural needs post TBI assessment and outcome measure.

2. Methods

2.1. Sample and data collection

A 46-item draft scale has been developed from verbatim quotes taken from transcripts of an earlier phase of the study and refined using a culturally responsive method [16]. Rangahau Kaupapa Maori (Maori research approaches determined and conducted by Maori, with the goal of supporting Maori health advancement) were utilized. The statements used in the first iteration of the tool came from Maori participants in marae wananga (traditional learning fora). The items were then refined via four focus groups with the final group of participants having experienced TBI. This was to ensure the items were acceptable to those with direct experience, that the items had face validity in addressing the sub-scale areas and were easily understood. The measure was then completed by 319 participants with lived experience of, or interest in TBI from a range of settings in the North Island of Aotearoa New Zealand between June and November 2015. They included attendees at Kura Reo; week-long total immersion Te Reo Maori wananga (Maori language learning environments) with a range of proficiencies in speaking Te Reo Maori from beginners to experts and face to face clinics of those with experienced of TBI in their whanau (see inclusion criteria below).

Table 1: Demographic characteristics of study participants

People were invited to participate in two ways. First, via Maori health service providers' appointments with the first author. Second, wananga groups were offered participation and the first author provided a presentation about the project, answered questions, and provided oversight of completion of the tool. Inclusion criteria were Maori with TBI, or non- Maori who were part of Maori whanau (extended families), for example by marriage, whanau members, friends of Maori with TBI, those with work connections with Maori with TBI and Maori community members concerned about TBI. TBI was defined by self-report as either confirmed, possible or unknown. Information was collected about TBI severity by mild, moderate, severe and unknown categories, however given the questionable accuracy of self-report, this data was not included in analysis. The emphasis here was on offering participation to whanau as well as to individuals affected by TBI. This reflects the centrality of whanau as a health and wellbeing construct which is well recognised in Maori scholarship [17] and tikanga (cultural lore) [18]. Indeed, the theoretical basis of this tool proposes that TBI affects the whole whanau and that the whole whanau needs to considered as “the patient” [3]. Participants provided written consent.

The research was approved by the ethics committee of the Health and Disabilities Ethics Committees (14/CEN/17) and the first author"s institution (EC14 034HE). Participants were supervised when completing the draft outcome measure by the first author or a research assistant. These data were then entered into the Rasch analysis software programme, RUMM2030 [19].

2.2. Instrument

The instrument resulting from the earlier research [3] contained four subscales and 46 items. The four subscales were labeled Wa (time), Wahi (place), Tangata (people) and Wairua practices (Wairua is defined here as an aspect of health and wellbeing characterized as a unique connection between Maori people and all aspects of the universe). Participants were invited to score each of the items as strongly agree, agree, disagree, or strongly disagree. While debate continues around whether to include a neutral response option in surveys or assessment tools, the rationale used here aligns with others who have shown absence of a neutral option encourages mental effort to engage with the item and negates the effect of social desirability bias [20]. Other demographic information was collected about each participant as presented in Table 1.

2.3. Data analysis

All analyses were carried out on each of the subscales using RUMM2030 [19] to determine the fit of the data to the Rasch model. Rasch analysis is a probabilistic mathematical model that draws on item response theory with the advantage of estimating the item difficulty and the person ability separately, which is not possible using measures based on Classical Test Theory [21]. The 1-parameter logistic function enables each item’s difficulty to vary, but assumes all items discriminate equally. Before Rasch analysis is used to transform ordinal observation data into linear measures, Rasch fit statistics are examined to enable assessment of any threats to linearity [22, 23]. Rasch analysis is used to assess the measurement properties of existing measures and to guide the development of new ones [24]. The Rasch model states that the outcome of an encounter between a person and an item is governed by the product of the construct of interest of the person together with the easiness of the item [25]. The person’s estimate of cultural needs is derived by dividing the percentage of items that scored highly, by the percentage of items scored in the low range, and then by taking the natural log. Scale items have a variable amount of difficulty. Items which capture difficulty are important because they make the measurement useful in a practical sense, capturing and discriminating high levels of need to be acted upon, and monitored. Likewise, items which capture low, and intermediate levels of need are important in a measure so that both lower and intermediate levels of need can be identified and that changes over time can be monitored and responded to. In the Rasch model, item difficulty is estimated by calculating the odds of success in identifying those who scored highly and those who scored in the low range. Each item within the scale has its own level of difficulty on the trait (item parameter) and every person has his or her own level of “ability/trait”. Item parameters are estimated independently from the person parameters and once they are identified they can be placed along the same interval scaled ruler. The item and person performance probabilities determine the interval sizes on the “ruler” of the measure.

Several tests were performed to assess the fit of the subscales to the Rasch model. Fit to the assumptions of the model can have a number of contributing factors which are explained in detail elsewhere [25-28]. It is important to note that ‘misfit’ should not be taken to mean that the item has no merit or is of no interest, but rather that it does not fit the unidimensional structure of a measure (or in this case domain). If this is the case, collapsing scores or moving an item to a different domain for items that do not fit but add discriminatory information is considered. Table 2 presents a brief overview of the central Rasch analytical concepts and the actions that can be taken in the case of conditions not being met for the transfer from ordinal to linear scores.

Table 2: Brief overview of Rasch analysis concepts (adapted from [24])

^AThresholds represent points where the probability of scoring either of the two adjacent categories is 50%. If it is not the case, one would observe disordered thresholds where the individual score cannot be reliably interpreted.

^BExtreme scores (much lower than -2.5, or much higher than 2.5) indicate issues with response pattern which may include: responding according to a socially desired norm, carelessness with responding or low motivation in responding. As such data would not add any meaningful information to the calibration process, it has been suggested to consider excluding extreme persons from the sample (Bond and Fox, 2001; Tennant and Conaghan, 2009).

^CLocal dependency occurs when a person"s response to one item is reflected in their response to another item.

^DTwo subsets of items are identified by PCA: one with positively loading items and one with negatively loading items. Two estimates derived from these subtests are then tested by using an independent t-test. If the result is insignificant at p≤0. 05, the unidimensionality is supported.

^ETargeting of the scale to the latent trait allows identification of floor and ceiling effects.

^FDIF occurs when people from different groups (for example, males and females) with equal amounts of the underlying trait do not respond to items in a similar manner.

^GA testlet is a bundle of items that share a common stimulus^42.

For Rasch analyses, reasonably well targeted samples of 150 are reported to have 99% confidence that the estimated item difficulty is within ± ½ logit of its stable (and n=243 for poorly targeted samples) [29] Our sample of 319 was therefore optimal for the purpose of this analysis.

3. Results

This section reports the analysis results of each Te Waka Kuaka subscale separately. There were no missing data in the data set.

3.1. Wa (time)

The proposed subscale had 9 initial items all concerned with the broad concept of time. These items were not specifically linked to issues such as time to access treatment or time since injury. Rather, time in this subscale is concerned with what needs to happen first in time, the role of time in facilitating healing, taking time for a range of purposes and flexibility of time schedules. The initial analysis of the Wa subscale showed that there were no items with statistically significantly disordered thresholds and the scale was unidimensional. However, the scale did not fit the Rasch model with a significant (p=0.0005) item-trait interaction chi-square and particularly high mean persons location (2.8; SD=1.5). Twenty-three percent (n=60) of the sample had extreme scores and so were deleted from the analysis, the remainder of n=259 provided a robust sample to analyse.

Deletion of the subgroup improved the mean persons location (2.3; SD=1.2) but did not result in an improvement in item-trait interaction. Further examination of the items revealed three (items 3, 5 and 9) misfitting the model. Item 3, “whakawhanaungatanga (the process of making connections with others) at the beginning sets the scene for the journey” functioned differently according to iwi (tribe), with the “other” group being an outlier. Also, the item did not fit the Rasch model with item fit residual of -2.825, and chi-square probability of 0.006. Importantly, the item seemed to identify issues already captured by items 1 (Starting the process of wairua healing is the first thing that needs to happen for our whanau), 2 (The journey of wairua healing is enhanced with time), and 8 (whakawhanaungatanga time builds, to keep hope and dreams alive). Hence, it was deleted from this subscale. Item 5, “It is important that kaimahi (health workers) are flexible in their schedules of work”, had a high fit residual (2.722; p=0.0006) indicating the item does not fit the scale. It was also deleted from the subscale. Lastly, Item 9, “Whanau unity and strength builds healing” showed local dependency problems with item 3 “whakawhanaungatanga at the beginning sets the scene for healing”. It also displayed non-uniform DIF for relationship (see Table 1). A number of possible solutions described in Table 3 were tested, however, only deletion of the item led to solving the local dependence with item 3.

These modifications improved the fit of the Wa subscale and provided the final solution (see Table 3). The resulting 6- item scale was unidimensional, and the item-trait interaction was non-significant (p= 0.1237). The reliability of the subscale is relatively low (PSI=0.56). The targeting of the subscale Wa was skewed, suggesting people on average scored towards the upper end of the scale (Figure1).

Table 3: Rasch analysis summary statistics

Abbreviations: PSI – Person Separation Index; extrms – extremes; alpha – Cronbach"s alpha. „First" refers to the analysis results of the raw ordinal data; „final" refers to the analysis results of the Rasch-transformed data.

Figure 1: Wa (time)

3.2. Wahi (place)

The proposed Wahi subscale included 10 items concerned with aspects to do with places, such as those of cultural significance as well as clinics and hospitals. The initial examination of the Wahi subscale found that the item-trait interaction chi-square was highly significant (p<0.00001) and the scale was not unidimensional. None of the items showed disordered response category thresholds. Further analysis of DIF and fit statistics revealed four items that required specific attention: items 10, 11, 16 and 17. Items 10, “The use of pepeha within treatment would support the healing”, and item 17, “Whanau from home are an essential link with home”, had uniform DIF by TBI severity. These items were combined into a testlet with item 13, “Whakaairo (carvings) teach important lessons that help with healing”, which had showed non-significant DIF in an opposite direction. This resulted in these opposing directional DIF cancelling each other out. Item 11, “Being inside buildings like hospitals does not help me”, had a very high fit residual of 7.785 (p<0.00001), demonstrating it did not fit the subscale. This item was therefore removed. Item 16, “Gathering, preparing and eating food from home is an important part of healing”, showed uniform DIF by location and TBI. This item was combined into a testlet with item 19 as this item visually showed to have DIF in the opposite direction (non-significant), “being on the marae is a good place to start to feel strong again”, and therefore these DIF in opposite directions cancelled each other out.

These modifications improved the subscales fit to Rasch model and provided the final solution (Table 3). The final subscale had 9 items and was unidimensional, the item-trait interaction was non-significant, and no DIF was observed. The reliability of subscale Wahi was good (PSI=0.78) and the targeting acceptable (Figure 2).

Figure 2: Wahi (place)

3.3. Tangata (people)

This subscale is concerned with people involved with the person with TBI and their whanau and had a total of 15 statements. The initial analysis of the Tangata subscale showed that the scale was unidimensional and none of the items had statistically significant disordering of response categories thresholds. However, the scale did not fit the Rasch model with statistically significant item-trait interaction chi-square (p=0.0002). Further examination revealed three pairs of items with high residual correlations. Item 22, “Within whanau there are a lot of resources”, was locally dependent (residual correlation = 0.25) on item 23, “within the whanau is the rongoa” (rongoa is the Maori word for medicine). From a theoretical point of view, these two items consider two very similar concepts. However, item 23 is focused more specifically on the healing process, whereas item 22 (Within whanau there are a lot of resources) is much less specific as to what sort of resources might be available, when and for what purpose. Furthermore, item 23 showed a better spread on the latent trait of interest (3.8 versus 2.8 logits). Therefore, item 22 was deleted from this subscale. Item 26, “Maori have a different point of view from Pakeha (non-Maori of European ancestry)”, was locally dependent upon item 27 (0.405) “Maori cultural needs are different from Pakeha”. Theoretically, cultural needs secondary to the culturally determined injury to wairua are critical to the functioning of this tool, in order to best understand how whanau conceptualise these needs. While asking about similar issues item 27 more specifically asks about cultural needs, whereas item 26 refers only to a different point of view. Hence, the decision was made to delete item 26. Item 28, “When health workers relate to the culture of the whanau outcomes are improved”, was locally dependent (residual correlation = 0.444) on item 29, “When health workers support whanau to address wairua outcomes are improved”. Item 29 was deemed to be theoretically more important, because it more directly measures the issue of wairua which is central to the theory of the cultural aspect of injury. Therefore, item 28 was deleted from the subscale.

Deletion of these three items improved fit of data to the model and provided the final solution (Table 3). The item-trait interaction chi-square was non-significant, the scale was unidimensional and no DIF was observed. The reliability of the subscale Tangata was good (PSI=0.740) and the targeting was acceptable (Figure 3).

Figure 3: Tangata (people)

3.4. Wairua practices

'Wairua practices' is a phrase used to describe activities that strengthen wairua. Wairua is an area of hauora (health and wellbeing) that conveys the unique connection between Maori and all aspects of the universe. While wairua is mentioned in other subscales, wairua is the primary focus of this subscale. This subscale consisted of 12 items. The initial analysis of the Wairua subscale found that the scale was unidimensional, but it did not fit the Rasch model (p<0.0001). Moreover, there was one misfitting item, one item showed nonuniform DIF, two items were locally dependent, and a number of items had statistically significantly disordered response category thresholds. Item 35, “Practices that strengthen wairua are as important as clinical interventions”, was found to be misfitting with chi-square p=0.00014. The item was deleted and fit to the model improved. Examination of item 46, “Use of Te Reo Maori means wairua is being strengthened”, identified non-uniform DIF by location and statistically significant disordering of response category thresholds. The decision was made to delete this item and this improved fit to the model. Items 43, “Romiromi (type of massage) can be a powerful healing tool”, and 42, “Mirimiri (type of massage) can be a powerful healing tool”, were found to be locally dependent (residual correlation = 0.638). Because these types of massage are very similar and mirimiri (massage) is more commonly known, item 42 was retained and item 43 was deleted. Five items 36, 38, 39, 44 and 45 showed statistically significant disordered thresholds. The lower two response categories (“strongly disagree” and “disagree”) of these items were collapsed into one category. This modification further improved fit of data to the model and provided the final solution for the Wairua subscale. The scale fit the model with non-significant item-trait interaction and was unidimensional. The reliability of the scale was good (PSI=0.733) and the targeting was acceptable (Figure 4). Scoring was modified accordingly.

Figure 4: Wairua practices (activities that strengthen spiritual connection)

3.5. Item Difficulty

Table 4 presents the relative difficulty of each item of the Te Waka Kuaka subscales. The easier the item, the higher the expected scores are for people with high levels of investigated construct.

Table 4: Item Difficulty.

4. Discussion

This study presents Rasch analysis of a new measure, Te Waka Kuaka, for use in Maori cultural needs assessment following traumatic brain injury. Given the over representation of Maori with TBI [1] alongside Maori beliefs about the sacred quality of the head, „he tapu te upoko", [18] such a scale is much needed. This investigation was done to examine the validity of Te Waka Kuaka. Our analysis identified ten items that did not fit the Rasch model and they were deleted. The resulting four subscales fit the Rasch model and were unidimensional. Very few measures developed to assess Maori specific aspects of health exist. One that has been used in mental health and addictions is called “Hua Oranga” [30]. The Hua Oranga operationalises a well know framework called “Te Whare Tapa Wha” (the four walled house). However, this framework does not have an underpinning theory. It proposes four constructs, whanau (extended family), wairua (spirituality), hinengaro (mind) and tinana (body) and whilst some analyses of the psychometric properties of this measure have occurred we are not aware of any previous measure of hauora being developed using Rasch analysis [8, 31]. In addition, the Hua Oranga measure explores a construct of general hauora, rather than four subscales based on a theory of brain injury.

From a clinical perspective, analysis of several of the items were of interest:

1. Item 3 highlighted that there were a range of groups for whom the item functioned differently, by iwi (tribal group) and with the “other” group being an outlier. One interpretation of this is that the small non-Maori “other” group had a different understanding of whakawhaunaungatanga. This is not unexpected given the concept is Maori-specific. Also, it is possible that differing iwi (tribal) groups conceptualise this activity in different ways. This finding added to a richer understanding of whanaungatanga itself.
2. Item 11, “being inside buildings like hospitals does not help me”, was a statement that came from the preliminary research. While this statement may have assisted in considerations about the location of rehabilitation processes, the item did not have explicit theoretical salience regarding the wairua aspects of the injury. These were considered better assessed by item 19 “being on marae is a good place to start to feel strong again”.
3. The negative frame of the statement (“does not help me”) was thought to contribute to a different perception of the item by participants, compared to the positively framed items. The lower PSI (0.56) of the Wa subscale indicates that most of the participants scored those items Given the heterogenicity of the participants as identified by the wide range of iwi (tribal) affiliations represented, arising from different parts of Aotearoa, New Zealand and in having a range of competencies in Te Reo Maori this indicates the importance of the concept of time and the likelihood that these items will be highly endorsed. The finding is of clinical importance. Recognition of responses to items in this subscale, especially those most strongly endorsed can directly inform priorities in subsequent management plans.
4. The spread of difficulty in the items of Te Waka Kuaka is relatively narrow, between -1 and 1 (see Table 4). Including deleted items did not affect the spread. Similarly, it is possible that because the methodology of deriving the items was culturally conservative, in other words, developed on marae (traditional meeting houses), albeit urban, rural and remote, that the items do not address Maori cultural needs that are either very easy and or very difficult to endorse. Given the positive skew in this sample, further testing could be undertaken with people who are less in touch with their Maori cultural identity. We hypothesise that sample would score more towards the lower end of the Te Waka Kuaka subscales.
5. A potential limitation of the study is that the wider sample of possible participants is unknown so no response rate can be calculated. However, given the large sample size the analysis itself remains robust.

Dissemination of the findings of the analysis with research partners, namely health and education providers in the Maori community, has led to widespread requests for use of Te Waka Kuaka in settings outside of TBI rehabilitation. This is an unexpected development. One approach being considered is to develop a further study protocol to collect this data. Analysis would then enable better understanding of the scope of the tool"s application. Clinical implications of the use of the tool are significant. By being able to identify the immediate needs of the whanau clearly and quickly, the whanau themselves and the health worker can focus on addressing those needs without delay. How these needs change can be easily reviewed, and this can in turn guide further tailoring of supports. Given the theoretical importance of addressing the cultural aspect of the TBI, the injury to wairua, ensuring these cultural needs across the four subscales are thoroughly monitored and responded to be vital. In this way, healing the cultural injury is likely to improve the recovery process, as well as outcomes for whanau.

5. Conclusion

Te Waka Kuaka is a new measurement scale that has been in development. This paper reports the Rasch analysis phase. Our findings show that the revised subscales are unidimensional and fit the Rasch model and that Te Waka Kuaka can now enable valid and accurate measurement of Maori cultural needs following TBI. Future research examining the responsiveness of Te Waka Kuaka would be a useful addition to better understanding applicability of this measure and its wider application.

Acknowledgements

The authors thank Te Hiku Hauora, Whakawhiti Ora Pai, Te Kura Reo ki Otaki, Te Kura Reo ki Kahungunu, Te Pinakitangi ki te Reo Kairangi, Kearoa Mokaraka, Raumahoe Ani Morris, Whaea Moe Milne, Health Research Council of NZ.

Conflict of interest

The authors declare that there is no conflict of interest regarding the publication of this paper. Subsequent to the funding of this study McPherson became Chief Executive of Health Research Council of NZ.

References

1. Feigin V L, Theadom A, Barker-Collo S L, et al . for the BIONIC Study Group. Incidence of traumatic brain injury in New Zealand: a population-based study. The Lancet Neurology (Internet) (2012): 70262-70264.
2. 28th Maori C Company haka (2011).
3. Elder H. Indigenous theory building for Maori children and adolescents with traumatic brain injury and their extended family. Brain Impairment 14 (2013a): 406-414.
4. Elder H. Te Waka Oranga. An indigenous intervention for working with Maori children and adolescents with traumatic brain injury. Brain Impairment 14 (2013b): 415-424.
5. Elder H, Kersten P, McPherson K, et al. Making time: deeper connection, fuller stories, best practice. Annals of Psychiatry and Mental Health 4 (2016): 1079-1082.
6. Norup A, Perrin P B, Cuberos-Urbano G, et al. Family needs after brain injury: a cross cultural study. Neurorehabilitation 36 (2015): 203-214.
7. Harwood M. Rehabilitation and indigenous people: The Maori experience. Disability and Rehabilitation 32 (2010): 972-977.
8. Harwood M, Weatherall M, Talemaitoga A, et al. An assessment of the Hua oranga outcome instrument and comparison to other outcome measures in an intervention study in Maori and Pacific people following stroke. New Zealand Medical Journal 125 (2012): 1-11.
9. Elder H. An examination of Maori tamariki (child) and taiohi (adolescent) traumatic brain injury within a global cultural context. Australaisian Psychiatry 20 (2012): 20-23.
10. Dudley M. (2016). Developing a Maori theory of dementia as the basis of culturally robust neuropsychological testing for ageing Maori 132 (2016): 66-74.
11. Ogden J, and McFarlane-Nathan. Cultural bias in the neuropsychological assessment of young Maori men. New Zealand Journal of Psychology 26 (1997): 2-12.
12. Puente A E, Perez-Garcia M, Vilar-Lopez R, et al. (2013). Neuropsychological Assessment of Culturally and Educationally Dissimilar Individuals. In En Paniagua & A.-M. Yamada (Eds.), Handbook of Multicultural Mental Health: Assessment and Treatment of Diverse Populations (2013): 225-241.
13. Durie, M. Understanding health and illness: research at the interface between science and indigenous knowledge. International Journal of Epidemiology 33 (2004): 1138-1143.
14. Friedly J, Akuthota V, Amtmann D, et al. Why disability and rehabilitation specialists should lead the way in patient-reported outcomes. Archives of Physical Medicine and Rehabilitation 95 (2014): 1419-1422.
15. Reeve B B, Wyrwich K W, Wu A W, et al. ISOQOL recommends minimum standards for patient-reported outcome measures used in patient-centered outcomes and comparative effectiveness research. Quality of Life Research 22 (2013): 1889-1905.
16. Elder H, and Kersten P. Whakawhiti korero, a method for the development of a cultural assessment tool, Te Waka Kuaka, in Maori traumatic brain injury. Behavioural Neurology (2015): 1-8.
17. Durie Mauri ora, dynamics of Maori health. Auckland: Oxford University Press (2001).
18. Moko-Mead Tikanga Maori, living by Maori values. Wellington: Huia (2003).
19. Andrich D, Sheridan B, and Luo G. RUMM2030 (Comupter Software and Manual). Perth, Australia: RUMM Laboratory 2030 (2010).
20. Krosnick J A, Holbrook A L, Berent M K, et al. The impact of" no opinion" response options on data quality: Non- attitude reduction or an invitation to satisfice? Public Opinion Quarterly 66 (2002): 371-403.
21. Hays R D, Morales L S, and Reise S P. Item response theory and health outcomes measurement in the 21st century. Medical Care 38 (2000): 1128-1142.
22. Haigh R, Tennant A, Biering-Sorensen F, et The use of outcome measures in physical medicine and rehabilitation within Europe. Journal of Rehabilitation Medicine 33 (2001): 273-278.
23. Whiteneck GG, Dijkers MP, Heinemann AW, et al. Development of the Participation Assessment with Recombined Tools–Objective for use after traumatic brain injury. Archives of Physical Medicine and Rehabilitation 92 (2011): 542-551.
24. Czuba K, Kersten P, Kayes N, et al. Measuring neurobehavioural functioning in people with traumatic brain injury: Rasch analysis of neurobehaviural functioning inventory. Journal of Head Trauma Rehabilitation (2015).
25. Bond T G, and Fox C M. Applying the Rasch Model. Fundamental Measurement in the Human Sciences. London, England: Lawrence Erlbaum Associates (2001).
26. Andrich D. Rasch Models for Measurement Series: Quantitative Applications in the Social Sciences No. 68. London, England: Sage Publications (1988).
27. Kersten P, and Kayes N M. Outcome measurement and the use of Rasch analysis, a statistics-free introduction. New Zealand Journal of Physiotherapy 39 (2011): 92-99.
28. Tennant A, and Conaghan P G. The Rasch measurement model in rheumatology: what is it and why use it? When should it be applied, and what should one look for in a Rasch paper? Arthritis Rheumatology 57 (2007): 1358-1362.
29. Linacre J Sample size and item calibration [or Person Measure] stability. Rasch Measurement Transactions 7 (1994): 328.
30. Durie M, and Kingi T A framework for measuring Maori mental health outcomes. Retrieved from Wellington (1997).
31. McClintock K, Mellsop G, and Kingi Development of a culturally attuned psychiatric outcome measure for an indigenous population. International journal of Culture and Mental Health (2011): 1-16.