Imagine that you want to compare a new diet for tadpoles that are reared in the laboratory to the traditional laboratory diet of boiled lettuce. You want to decide if the new diet will be associated with an increase in the average weight of the tadpoles. The new diet is a meat-based commercial fish food. In your experiment you keep all other factors, such as tadpole density, temperature, pH, amount of food, etc., constant. The only difference between your control and experimental groups is the type of food the tadpoles receive. Write a null hypothesis for this experiment: Write an alternate hypothesis for this experiment: What is the independent variable? What is the dependent variable? Would you want to test only one pan of tadpoles fed lettuce, and only one pan of tadpoles fed meat? Why or why not? After you weighed your tadpoles at the end of the experiment, how would you determine if the type of diet significantly affected tadpole size?

Hypothesis: There will be a significant difference between the tadpole weight gain before applying the commercial fish-based diet and the measures after some diet to the diet.

Null hypothesis: There is no significant difference in the means of the tadpole weight before and after the commercial fish-based diet.

Alternative hypothesis: There is a significant difference in the means of the tadpole weight before and after the commercial fish-based diet.

The independent variable is the amount of the commercial fish-based diet given to tadpoles, since it is the variable that is controlled in the experiment. The dependent variable is the tadpole weight gain, since it is the variable that is investigated and measured.

The gain or not in tadpole weight is the variable that we would use to know if the change in diet affects the size of the tadpole.

Explanation: