Question

researchers conduct a study to measure the effect of sunlight on levels of vitamins in participants’ bodies. match each type of variable with its example in this study. participants are randomly assigned to eight hours, four hours, or zero hours of sunlight exposure. the levels of vitamin d and calcium in the participants’ bloodstreams are measured. some participants eat a diet high in calcium, and other participants do not, but experimenters are not intentionally manipulating their diets. left side: \confound\, \dependent variable\, \independent variable\ in yellow boxes on blue background

Explanation:

• Independent variable: The independent variable is the one that is manipulated or controlled in a study to observe its effect on another variable. In this study, the amount of sunlight exposure (eight hours, four hours, or zero hours) is what the researchers are manipulating, so "Participants are randomly assigned to eight hours, four hours, or zero hours of sunlight exposure" matches the independent variable.
• Dependent variable: The dependent variable is the one that is being measured or observed to see how it changes in response to the independent variable. Here, the levels of vitamin D and calcium in the participants' bloodstreams are being measured to see the effect of sunlight, so "The levels of vitamin D and calcium in the participants' bloodstreams are measured" matches the dependent variable.
• Confound: A confound is an extraneous variable that can affect the relationship between the independent and dependent variables. In this case, the participants' diet (some eating a diet high in calcium and others not, which is not intentionally manipulated) can affect the vitamin and calcium levels, so "Some participants eat a diet high in calcium, and other participants do not, but experimenters are not intentionally manipulating their diets" matches the confound.

Answer:

• Independent variable: Participants are randomly assigned to eight hours, four hours, or zero hours of sunlight exposure.
• Dependent variable: The levels of vitamin D and calcium in the participants' bloodstreams are measured.
• Confound: Some participants eat a diet high in calcium, and other participants do not, but experimenters are not intentionally manipulating their diets.