Question

1. heidi is a chocolate lover and eats chocolate daily. she has a bad break - out and her friend told her eating chocolate causes pimples. heidi continues to eat chocolate every day for 2 weeks and counts the number of pimples she has on her face. the following 2 weeks she doesnt eat any chocolate and counts the number of pimples on her face.

a. independent variable =
b. dependent variable =
c. control =

1. ruthie has a pet goldfish. after several months the goldfish quits growing. ruthies mom told her the goldfish might have stopped growing because the tank is too small. ruthie measures the size of her goldfish in its current tank, and then puts the goldfish in a larger tank. after 2 months the goldfish is now 1cm longer.

a. independent variable =
b. dependent variable =
c. control =

1. nicholas has been biting his nails since he was a kid. he wants to break the habit so he puts bitter tasting nail polish on his left hand and leaves his right hand without polish. after 3 days he notices his nails on his left hand have grown but he continued to bite his right hand nails.

a. independent variable =
b. dependent variable =
c. control =

Explanation:

Problem 8 (Heidi and Chocolate/Pimples)

• Independent Variable: The factor that is manipulated. Here, it's whether Heidi eats chocolate (eating chocolate vs. not eating chocolate).
• Dependent Variable: The factor that is measured (depends on the independent variable). This is the number of pimples on her face.
• Control: Elements kept constant to ensure a fair test. Heidi's daily routine (other than chocolate consumption) and the time period (2 weeks of eating, 2 weeks of not eating) are controlled, or more specifically, the time she counts pimples (2 - week periods) and other non - chocolate factors affecting pimples.

• Independent Variable: The factor changed. Here, it's the size of the goldfish tank (current tank vs. larger tank).
• Dependent Variable: The factor measured (depends on the tank size). This is the length (growth) of the goldfish.
• Control: Elements kept constant. The goldfish itself (same goldfish) and the time period of observation (2 months) are controlled.

• Independent Variable: The factor manipulated. Here, it's the application of bitter - tasting nail polish (on left hand, not on right hand).
• Dependent Variable: The factor measured (depends on the nail polish). This is the nail - biting behavior (whether Nicholas bites his nails on each hand).
• Control: Elements kept constant. Nicholas' normal activities and the time period of observation (3 days) are controlled. Also, the fact that it's Nicholas' own nails (same person) is a control.

Answer:

a. Independent Variable = Chocolate consumption (eating chocolate or not)
b. Dependent Variable = Number of pimples on Heidi's face
c. Control = Time period of observation (2 weeks), Heidi's other daily habits (excluding chocolate eating)

Problem 9 (Ruthie and Goldfish Tank)