Using factor analysis for validity assessment: practical considerations.

A synthetic bidirectional expression module was constructed by placing a computationally designed minimal promoter sequence on the 5' and 3' sides of a transcription activation module. The activation of transcription from the unidirectional and bidirectional promoters constructed from the same sequence elements was evaluated by using the reporter genes gusA and gfp. The analysis based on transient and stable transformation of tobacco showed that the artificially designed multifactorial activation module activated transcription simultaneously to comparable levels in both the directions. The transcription activation module responded to elicitors like salicylic acid, NaCl and IAA in the forward as well as reverse directions. The concentration of the elicitor required for highest gene activation was similar for the two directions in case of the three activators. The kinetics of time of induction was similar in the two directions for salicylic acid and NaCl. In the case of IAA, the transcription activation was faster in the reverse direction. The results show that constitutive and chemically inducible bidirectional promoters can be deployed for predictable simultaneous regulation of two genes for genetic engineering in plants.

Factor Analysis, Statistical↗

PubMed2005

Determination of the origin of unknown irradiated nuclear fuel.

An isotopic fingerprinting method is presented to determine the origin of unknown nuclear material with forensic importance. Spent nuclear fuel of known origin has been considered as the 'unknown' nuclear material in order to demonstrate the method and verify its prediction capabilities. The method compares, using factor analysis, the measured U, Pu isotopic compositions of the 'unknown' material with U, Pu isotopic compositions simulating well known spent fuels from a range of commercial nuclear power stations. Then, the 'unknown' fuel has the same origin as the commercial fuel with which it exhibits the highest similarity in U, Pu compositions.

Factor Analysis, Statistical↗

PubMed2005

The structure of negative symptoms within schizophrenia: implications for assessment.

This review examines the structural validity of negative symptoms focusing on 2 questions: (1) Do negative symptoms represent a domain separate from other symptoms in schizophrenia? and (2) Within negative symptoms, is there a structure that suggests multidimensionality? Results from exploratory and confirmatory factor analytic studies are examined to address these questions. Across studies and symptom instruments, negative symptoms appear to consistently emerge as a factor separate from other dimensions of the illness in schizophrenia. Whether 2-, 3-, or 5-factor models are identified, negative symptoms consistently load on a factor separate from positive symptoms, affective symptoms of depression or anxiety, and symptoms of disorganization. Focusing on negative symptoms themselves, factor analytic findings suggest that this construct is multidimensional with at least 2 factors (involving diminished expression and anhedonia-asociality). Although these factors were replicable, serious limitations were noted in this literature. Thus, 2- (or even 3- or 5-) factor models of negative symptoms should not be considered definitive, but rather all converge to support the general conclusion of the multidimensionality of negative symptoms. The later findings indicate the importance of employing assessments that provide adequate coverage of the broad domain of negative symptoms. Importantly, caution is noted in the interpretability of findings based on existing instruments, and implications for future assessment are discussed.

Factor Analysis, Statistical↗