Methodological differences in data collection and different ascertainment of behavioral information between CCC and JHU may also have affected our findings.
Thus, variation in concentration may be attributable to local nature of crime (Weisel 2005) or to differences in data collection processes between different surveys (Lee 2000).
With regard to quality measurement, differences in data collection methods (chart audit, claims data, newly collected data, etc).
Looking for reasons was difficult, due to differences in data collection: UK income is recorded for families, Sweden's for individuals.
The 1990 census showed 44percentt of the foreign-born were from Latin America, and 23percentt were from Europe, although the numbers are not directly comparable with 2000's because of differences in data collection.
This inconsistency was attributed to a variety of factors, including differences in data collection mechanisms and product use factors.
Though standard definitions were used, biases related to differences in data collection between the centers cannot be ruled out.
Despite these differences in data collection and ideas Gooderham and Nordhaug (2003 144) suggest 'some dimensions can be compared on account of their similarity'.
In the case of this study, we speculate that the general trend of lower nausea rates in the PLM database compared to those reported in corresponding medication labels is driven largely by differences in data collection mechanisms.
Thereby, we can establish that the lower accuracy may partly be due to differences in data collection, but also that the APPS cannot be generalized to other populations due to over-fitting to the derivation population.
Differences in reporting rates of nausea between medication labels and in the PLM database may be influenced by various factors, including methodological differences in data collection and differences in indications for medication use.
