Sample size planning is important because it helps to ensure that your study will .

		Have sufficient statistical power
		Be able to detect an effect when an effect is actually present
		Reduce the effects of certain biases.
		All of the above

Range restriction occurs when the range of values observed in a variable's distribution has been and, thus, can its correlation with another variable.

		Condensed; weaken
		Expanded; weaken
		Condensed; strengthen
		Expanded; strengthen

Statistical power tells you the probability of observing effect when an effect is actually present.

True

False