A researcher is interested in whether touch therapy improves the weight gain of preterm infants. They provide touch therapy to a sample of 30 preterm infants. After two weeks, they compare the change in weight to the expected weight gain (a previously determined mean weight gain for preterm infants of this age).

a. What is the independent variable?

b. What is the dependent variable?

c. What is the research hypothesis? (Note that the research hypothesis is also called the "alternative" hypothesis and can be written as H_a.)

d. What is the null hypothesis? (Note that the null hypothesis can be written as H₀.)

e. If the difference (between the weight gain of this sample of infants and the expected weight gain based on a known average) is statistically significant, would the researcher reject the null hypothesis or fail to reject it?

f. If the researchers reject the null hypothesis, what is their conclusion?

g. If the researchers fail to reject the null hypothesis, what is their conclusion?