A company that manufacturer puppy food wants to determine which food chow food, Chow A or Chow B makes puppies grow bigger how would I design a experiment for this answer?and identify the independent and dependent varible and constant?
A scientific experiment should test for only one variable (change) at a time in order to determine what is causing the results. All other variables should be held constant (the same).
Therefore, when testing which type of dog food is causing the puppies to grow larger, the only variable that I would change would be the type of dog food.
I would have two groups (Group A and Group B), each with the same number of dogs (say 250... the larger the population size, the better) and give each group a different kind of food. However, the same amount of food would have to be given for each Group. Each group would receive the food for a certain period of time, after which the average growth (measured as weight gain) per group could be calculated. Therefore, the amount of food, the size of the groups, and duration of feeding would be constants (things that are the same amongst each group) of the experiments.
An independent variable is one that the experimenter changes (manipulates). In this experiment, the type of dog food administered per group would be the independent variable.
The dependent variable is that which depends on the independent variable. It is the one that is being measured by the experimenter. In this lab, the average weight gain per group would be the dependent variable.