Hi, Do you know what type of Scefflera it is and is it inside or out?

It's indoor plant, called Australian ivy palm.

Schefflera actinophylia then. These are the conditions it likes:
Average warmth, minimum 55 degF in winter, not keen on temperatures above 70 deg F any time. Keep out of direct sun, but in good daylight, and away from any heat sources such as radiators. Water liberally from Spring through to Autumn, and sparingly in winter. Mist leaves frequently. Repot in Spring every 2 years.

Regarding watering in winter - water when the surface of the compost is dry to the touch, but not so dry that its shrunken from the sides of the pot. Empty out any outer container or pot after 30 minutes so that the plant is not left sitting in water.

Sudden changes in light or temperature can also cause leaf drop, though it is not as sensitive to that as a Ficus tree. Definitely keep away from doors, or windows that are periodically opened, and don't move it from room to room, "to give it light", like my neighbor does! : )
As Bamboo says, good drainage is critical, and leaving it sitting in water is often fatal.
Low light can also cause leaf drop--I would keep it within 2 meters of a window, and not off to one side.