The confusion about the prognostic value is mainly due to the difficulty in comparing analyses.
However, the difficulty in comparing the two nuclear arsenals, which differed in important respects, resulted in long and complex negotiations.
The small patient sample sizes and varying male populations also add to the difficulty in comparing studies.
Finally, within this review we have not reported on the speed of the models, largely due to the difficulty in comparing models developed on different hardware and with different objectives.
Others raised substantive concerns about regulation of overseas clinics, genetic testing, standards for egg donors and language barriers, not to mention the difficulty in comparing pregnancy rates in American clinics with those abroad.
David Karol, a professor of government and politics at the University of Maryland, sees difficulty in comparing Trump to anyone who has sought the GOP nomination in recent years.
Currently, a variety of different devices have been developed to transfect cells in vitro, resulting in a lack of standardized experimental conditions and difficulty in comparing results from different laboratories.
Different accounting rules and principles could also cause difficulty in comparing two companies.
The current assessments are all based on internal measures and this causes difficulty in comparing data from different sources.
Another limitation that adds difficulty in comparing treatments is the lacking consensus on several definitions between studies.
But as even the ILO concedes, there is huge difficulty in comparing national data, which is often inconsistent, incomplete or simply unavailable.
