Question

identifying
read through the following scenarios. identify the control group, the experimental group, the independent variable, and the dependent variable.
scenario
a company wants to test a new dog food that is supposed to help overweight dogs lose weight. 50 dogs are chosen to get the new food, and 50 more continue their normal diets. after one month, the dogs are checked to see if they lost any weight.
a new sunscreen has been developed that is supposed to be more effective at preventing sunburn. 30 participants spray one arm with the new formula, and spray the other arm with the leading formula. after 4 hours in the sun, their skin is evaluated for any redness.
a student wants to study the effect of sunlight on plant growth. in his experiment, 12 plants receive normal amounts of sunlight, but half of them are kept under bright sun lamps all night long. after 6 weeks, the plants heights are measured.

Explanation:

Step1: Define variables and groups for dog - food scenario

The independent variable is what is being changed. Here, it's the type of dog food. The dependent variable is the result that is measured, which is the weight loss of the dogs. The experimental group gets the new dog food, and the control group gets the normal diet.

1. Type of dog food (new dog food or normal diet)
2. Weight loss of dogs
3. 50 dogs getting new dog food
4. 50 dogs on normal diet

Step2: Define variables and groups for sunscreen scenario

The independent variable is the type of sunscreen formula. The dependent variable is the presence or absence of sunburn (skin redness). The experimental group has the new sunscreen formula, and the control group has the leading formula.

1. Type of sunscreen formula (new or leading)
2. Skin redness (presence of sunburn)
3. Arm with new sunscreen formula
4. Arm with leading sunscreen formula

Step3: Define variables and groups for plant - growth scenario

The independent variable is the amount of light (normal sunlight vs. normal sunlight + sun - lamps at night). The dependent variable is the height of the plants. The experimental group has plants with extra light from sun - lamps, and the control group has plants with normal sunlight only.

1. Amount of light (normal sunlight or normal sunlight + sun - lamps at night)
2. Plant height
3. Plants with normal sunlight + sun - lamps at night
4. Plants with normal sunlight only

Answer:

1. Type of dog food (new dog food or normal diet)
2. Weight loss of dogs
3. 50 dogs getting new dog food
4. 50 dogs on normal diet
5. Type of sunscreen formula (new or leading)
6. Skin redness (presence of sunburn)
7. Arm with new sunscreen formula
8. Arm with leading sunscreen formula
9. Amount of light (normal sunlight or normal sunlight + sun - lamps at night)
10. Plant height
11. Plants with normal sunlight + sun - lamps at night
12. Plants with normal sunlight only