A company that sells hair-care products wants to determine if a product that combines shampoo and conditioner works better than a shampoo and conditioner used separately. A researcher recruits 60 volunteers and pairs them according to age, hair color, and hair type. For each pair, the researcher flips a coin to determine which volunteers will use the shampoo/conditioner combination and which ones will use the separate shampoo and conditioner. After using the products for one month, the subjects are asked to rate their satisfaction with the hair products on a scale of 1 – 10 ( 1 is equal to highly dissatisfied and 10 is equal to highly satisfied). What type of sampling is described in this study?
The researcher matches volunteers into pairs with similar age, hair color, and hair type, then randomly assigns one person in each pair to each product treatment. This creates paired data: each person’s satisfaction rating can be compared with the rating of their matched partner. The correct choice is paired data.
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