Due to
Due to the influx of factors… It was due to the influx of factors that… It seems possible that the results are due to…
Because
The correlation between X and Y is interesting because… X has been studied over the last few decades because
Since
Since the battle of Tinchebrai in 1106… Since X is a factor in this type of context…
As
As the battle of Tinchebrai demonstrates… As long as these conditions are present, we can predict that…