El valor de la evidencia: manuales, huellas y valoraciones

Carr (1994) describes quantity as a measure or a numerical collection of meaning that, when contrasted with other similar sets of data from similar sample groups, becomes increasingly powerful. Quantitative research is concerned predominantly with the collection and analysis of data that can be presented numerically through validated processes, for example, confirmatory data analysis (CDA) (Van de Geer 1993). Accumulation therefore adds to the overall significance of data. In order to do this pre-specified questions are necessary and data collection techniques are subsequently orientated around the discovery of specific information. On the other hand qualitative analysis of data examines inherent properties and dimensions that may be less measurable than quantitative data (Miles & Huberman 1994) but of sufficient resonance to promote an understanding of the experience of the research participant.

Among the range of qualitative approaches grounded theory methodology is designed to reveal a wide range of findings from which a substantive theory can emerge. Exploratory data analysis (EDA) (Turkey 1977; Velleman & Hoaglan 1981) is an example of data being presented in diagrammatical or illustrative form (Robson 2003). This I viewed as potentially helpful in organising both data analysis and findings. Equally the presentation of findings may provide greater clarity for the reader. It was anticipated that both descriptive, and to a limited extent, measurable findings would be presented since the study examines both the properties and dimensions of dual diagnosis. A qualitative study, presented in this manner may hold appeal to readers of both qualitative and quantitative dispositions.

Polarised views based upon the general assertions above (Sandelowski 1995) have inclined researchers to adopt a methodological philosophy consistent with their personal worldview (Robson 2003), either a perspective emphasising importance through proof and probability or an explanatory model that promotes feasibility and understanding.

Gephart (1998) pragmatically suggests that neither research methodology can be certain of capturing the essence of the situation or field under study. The notion therefore exists that a primary and supplementary approach, for example qualitative

and quantitative combined (Breitmayer et al 1993), could fulfil the ambitions of a researcher wishing to explain or describe both a situation and indicate associated probabilities in relation to frequency and size, for example.

The mixing of methods alluded to above has been described as a unique blend by some (Swanson-Kauffman 1986) and a ‘sloppy’ even though ‘do-able’ approach by others (Morse 1991). Whilst limited evidence is available as to the appropriateness of mixed methods of research (Maggs-Rapport 2000), Glaser and Strauss (1967) introduced an analytic process enabling dense text to undergo structured and interpretive analysis.

Glaser and Stauss claimed that, as a result, grounded theory research could be generalisable to other people and other settings despite the goal of generalisability being de-emphasised. In quantitative research generalising findings to larger populations or samples is a chief goal (Oppenheim 1992) and subsequently time and energy is spent obtaining a sizable, measurable, describable sample, at random, in order to accurately match such a sample (and its related findings) to a ‘real life’ group or situation. Therefore quantitative research has established the standard for generalisability of findings (Brighton et al 2003) to matched samples. In practical application however it may be deficient when the accuracy of matching diminishes. For example when operationally applied to a broader sample which lacks the specific inclusion and exclusion criteria on the grounds of its aetiological or demographic profile (Bowling 2000).

Qualitative studies, selecting small purposeful samples, have also been considered non-representative of wider populations and subsequently generalisability deemed weak. Morse (1991) claimed that since generalisability was not a primary goal of qualitative research its findings hold little widespread significance. However, a positivist investigation aspiring to statistical significance in its research answer may be of little or no value when applied to a social construct such as ‘care’ (of those who are ill, disabled or disadvantaged for instance), a construct arguably that lacks a precise measurable description yet conveys an essentially understandable meaning to the world. Therefore the variability of personal experiences and responses to stimuli

complexities and differences among a given sample and, furthermore, may over simplify findings.

Strauss and Corbin (1998) proposed a structured methodology that organises data by participant experienced incidents, where numerous incidents may relate to one category or concept and several categories or concepts may exist for several participants. The accumulation of hundreds of incidents from a relatively small sample (20 participants for example) not only achieves a numerical strength but can also reveal wider and deeper information of an undetermined nature. To claim generalisability then, according to Strauss and Corbin, is part accumulation, to the point of saturation (where no new information or concepts are emerging) and essentially, part representativeness throughout the sample of the phenomenon under enquiry.

Glaser (1978), in the absence of Strauss, later focuses upon the importance of a purposeful sample. A sample that contains characteristics of the phenomenon under study has the potential to reveal the comprehensive, in-depth and broad data set necessary to explain the phenomenon, thus suggesting that theoretical explanations would not be forthcoming in a study methodology that had pre-specified questions or hypotheses. After all, the depth and breadth of information is largely unknown at the outset.

The debate centred on the advantages and disadvantages of quantitative and qualitative methodologies is partially academic in this study since I have concluded, like many others (Bond 1992; Koch 1996; Morse 1991) that a research methodology should be chosen to suit the area of enquiry. Given that research findings gain significance through their accumulation no study alone can provide a comprehensive answer. Given also, that my area of study and work lacked conclusive literature findings to generate satisfactory hypotheses, it appeared appropriate to select a methodology that would enable a theory to be developed that related to a vast, but as yet, unspecified range of variables (Glaser 1978).

I would conclude then that dual diagnosis is under-researched (DH 2002, Schulte & Holland 2006) and for this reason hypothetical questions would be based more on

speculation than prior research. In other words it is implausible to test a theory where none exist. The sphere of dual diagnosis in practice terms however, is familiar to many service users, practitioners and carers. Grounded theory by its empirical observations and structured analysis (Glaser & Stauss 1967; Strauss & Corbin 1998) provides a basis on which to investigate uncharted waters in a familiar situation in order to offer an explanation that has potential to include all variables, known, suspected and unknown.