Why must a scientific explanation be supported by data

In an experiment examining the effects tai chi on arthritis pain, callahan (2010) selected a large sample of individuals with doctor-diagnosed arthritis. half of the participants immediately began a tai chi course and the other half (the control group) waited 8 weeks before beginning. at the end of 8 weeks, the individuals who had experienced tai chi had less arthritis pain that those who had not participated in the course.

Anonnative species is best described as a species that a. does not normally live in an area b. has no permanent home c. is a poor predator d. increase biodiversity

Which factor affects the force of gravity between objects? check all that apply. direction distance mass shape time