The phrase "a combination of active" is not complete and lacks context, making it difficult to assess its correctness in written English.
It could be used in contexts discussing various elements or factors that are combined, particularly in fields like science, fitness, or project management.
Example: "The study focused on a combination of active ingredients that enhance the effectiveness of the medication."
Alternatives: "a mix of active" or "a blend of active".
These studies involve following a group of study participants (ideally representative of the target population of interest) over time with a combination of active and passive surveillance activities to measure a variety of malaria indicators.
For most health outcomes, the report of 2008 Physical Activity Guidelines for Americans (2008 Guidelines) recommends a combination of active time equivalent to at least 150 minutes of moderate activity a week.
This instrument combines new detector materials, an innovative sensor geometry, and a combination of active and passive shielding to obtain accurate measurements of highly penetrating protons in an instrument compact and light weight enough for space flight.
As this type of training equipment can be used actively or with electrical motor support, it allows a combination of active and passive bicycle training.
That requires a combination of active diplomacy and military deterrence.
Beguines thus led a mixed life, with a combination of active and contemplative elements.
The research team will develop a system using a combination of "active" radio-frequency identification readers and "passive" tags.
Figure 4 shows observation results from two illustrative classes: one that is primarily lecture-based and one in which a combination of active-learning strategies are used.
This example represents a combination of active-constructive (talking with the person you are angry with) and passive-constructive (using time to cool down) strategies of anger regulation (Rivers et al. 2007): I think, you know, if you are really angry, I think you can say it.
The mechanisms responsible for reprogramming of DNA methylation are likely to be complex and involve a combination of 'active' and 'passive' processes, but are not yet fully understood.
