Mind mapping in qualitative research.

BACKGROUND: We tested a theory that mind mapping could be used as a tool in qualitative research to transcribe and analyse an interview. METHOD: We compared results derived from mind mapping with those from interpretive phenomenological analysis by examining patients' and carers' perceptions of a new nurse-led service. RESULTS: Mind mapping could be used to rapidly analyse simple qualitative audio-recorded interviews. CONCLUSION: More research is needed to establish the extent to which mind mapping can assist qualitative researchers.

Linear regression modeling of rim area to discriminate between normal and glaucomatous optic nerve heads: the Bridlington Eye Assessment Project.

PURPOSE: To create a diagnostic algorithm by modeling the normal variability of rim area (measured by Heidelberg Retina Tomography) using linear regression in normal elderly subjects. METHODS: Multiple linear regression was performed between log rim area and disc area, age, and sex in 712 normal elderly subjects. The relationship between log rim area and disc area was not linear and showed significant heteroscedascity (increasing variability of rim area with increasing disc area). These factors violate the assumptions of linear regression as performed by the Moorfields Regression Analysis (MRA), and were overcome by conducting linear regression separately for each disc area quartile. Actual rim area in each disc sector was compared with the 95% lower limit predicted by the analysis in the normal subjects and 58 glaucoma patients. RESULTS: Specificity and sensitivity of the New Regression Analysis (NRA) was 83% and 81%, respectively (84.4% and 82.7%, respectively for MRA). NRA specificity was unaffected by disc size (81.6% and 86.3% in the smallest and largest disc area quartiles, respectively, P=0.36). MRA specificity was reduced in larger discs (91.1% and 73.1% in smallest and largest disc area quartiles, P<0.001), with reduced sensitivity in smaller discs (58.3% and 85.0% in smallest and largest quartiles, P=0.05). CONCLUSIONS: Nonlinearity and heteroscedascity in the relationship between log rim area and disc area explain reduced specificity of the MRA in bigger discs as a statistical error. Although overall not offering better diagnostic performance, the NRA performed consistently across different disc sizes, offering better performance than the MRA in large discs.

Improving the accuracy of intraocular pressure readings.

AIM: To discover whether a protocol for calibration can improve the accuracy of intraocular pressure measuerements. METHOD: A protocol for checking the calibration of equipment was implemented in an ophthalmic outpatient department. After seven months, calibration checks were compared with those done on equipment in other ophthalmic areas that were not following a protocol. RESULTS: There was a statistically significant association between errors and areas not following the protocol (p = 0.02). In comparing errors found in the area using the protocol with all other areas, a significant difference was evident at the test point of 20 mmHg (p = 0.003). CONCLUSION: Using a protocol significantly reduces calibration errors.