Bell R C, Low L H, Jackson H J, Dudgeon P L, Copolov D L, Singh B S
NH & MRC Schizophrenia Unit, Mental Health Research Institute of Victoria, Australia.
Psychol Med. 1994 May;24(2):335-45. doi: 10.1017/s0033291700027318.
Latent trait models were fitted to data for 149 schizophrenic or schizophreniform inpatients rated on the Scale for the Assessment of Positive Symptoms (SAPS) and the Scale for the Assessment of Negative Symptoms (SANS) using the Rasch Extended Logistic Model. It was found that a reduction in the numbers of rating categories, from six to three or four led to consistencies in response while deletion of several items led to consistent scales of symptoms that accorded with an item response characterization. Behaviours included in the final scales varied in the numbers of categories, and in the range of symptom level covered by a category. Relationships between scores representing symptoms were found to be modelled better by a factor structure that included a third overlapping 'cognitive' factor in addition to the now traditional positive and negative factors, than by the original positive and negative factors alone.
使用拉施扩展逻辑模型，对149名精神分裂症或精神分裂症样住院患者的数据进行潜在特质模型拟合，这些患者根据阳性症状评定量表（SAPS）和阴性症状评定量表（SANS）进行评分。结果发现，将评分类别数量从六个减少到三个或四个可导致反应的一致性，而删除几个项目可产生与项目反应特征相符的一致症状量表。最终量表中包含的行为在类别数量以及类别所涵盖的症状水平范围方面存在差异。研究发现，与仅使用原来的阳性和阴性因素相比，包含第三个重叠“认知”因素（除了现在传统的阳性和阴性因素之外）的因素结构能更好地模拟代表症状的分数之间的关系。
