Question

which type of study is useful in establishing cause-and-effect relationships?
○ observational studies because they are the only approach that allows the effect to be observed.
○ experimental studies because a single variable is altered, and only that variable’s effect is measured.
○ experimental studies because they alter multiple variables that can impact a given outcome.
○ observational studies because, if an effect can be observed, the effect’s cause can be identified.

Explanation:

To determine the correct answer, we analyze each option:

• Option 1: Observational studies observe without manipulation, so they can't establish cause - effect as they don't control variables. Eliminate.
• Option 2: Experimental studies involve manipulating one variable (independent variable) while keeping others constant, allowing measurement of its effect on the dependent variable. This is key for cause - effect.
• Option 3: Experimental studies typically manipulate one variable at a time (to isolate cause - effect), not multiple. Eliminate.
• Option 4: Observational studies can't identify cause from effect observation alone (many confounding factors). Eliminate.

Answer:

B. Experimental studies because a single variable is altered, and only that variable’s effect is measured.