In epidemiological studies using linear regression, it is often necessary for reasons of economy or unavailability of data to use as the independent variable not the variable ideally demanded by the hypothesis under study but some convenient practical approximation to it.
Unavailability of actual company absence data to use in lost productivity estimates.
One limitation of our study was the unavailability of actual company absence data to use in lost productivity estimates.
Other factors contributing to inconsistent condom use are reluctance to ask the partner to use a condom, condom unavailability, older age, drug use, alcohol intake, experiences of violence, financial difficulties, absence of HIV testing and being in a long term relationship [ 12– 17, 17– 17].
In bivariate analysis, reported reasons positively associated with risk situations were reluctance of the sex partner to use a condom and unavailability of condoms at a sexual encounter (see Table 2).
An important limiting factor of the needs-based approach is the unavailability of extensive epidemiological data, leading some authors to use an alternative approach based on utilization data.
Last, due to the unavailability of child-onset disability weights for hearing loss, we attempted to use adult-onset disability weights instead into the economic evaluation.
However, the use of the PMF-56 model is restricted by the unavailability of input climatic variables in many locations and the option is to use simple approaches with limited data requirements.
However, we have not been able to use those tools in our comparison analysis due to source code and data unavailability.
Others methods had not been used due to the unavailability of the program despite the indication in the corresponding papers or to impossibility to modify the source code to used our microarrays data.
