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Identify the experimental units, the explanatory and response variables, and the treatments. How can we reduce the rate of refusals in telephone surveys? Most people who answer at all listen to the interviewer's introductory remarks and then decide whether to continue. One study made telephone calls to randomly selected households to ask opinions about the next election. In some calls, the interviewer gave her name; in others, she identified the university she was representing; and in still others, she identified both herself and the university. For each type of call, the interviewer either did or did not offer to send a copy of the final survey results to the person interviewed. Do these differences in the introduction affect whether the interview is completed?

Step by step solution

01

Identify the Experimental Units

The experimental units in this study are the randomly selected households that received the telephone calls. Each household represents a unit in which the experiment is conducted.

02

Determine the Explanatory Variables

The explanatory variables in this experiment are the variations in the introduction during the phone call. Specifically, these include: (1) the interviewer giving her name, (2) the interviewer identifying the university she represents, (3) the interviewer identifying both herself and the university, and (4) the option of offering to send a copy of the survey results.

03

Identify the Response Variable

The response variable is whether the interview is completed. This outcome measures the effectiveness of different introduction strategies in reducing the rate of refusals.

04

Define the Treatments

The treatments are the combinations of the explanatory variables. These include scenarios where the interviewer uses different combinations of introductions (name, university, both) and whether or not they offer survey results. Each combination forms a distinct treatment that is tested.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Explanatory Variables

Explanatory variables, often known as independent variables, are the factors in an experiment that are manipulated or observed to determine their effects on the response variable. In the context of this study, the explanatory variables are the different approaches taken during the telephone introductions. These include:

• Whether the interviewer gives her name.
• If the interviewer mentions the university she represents.
• Whether both the interviewer and the university are mentioned.
• The option to offer a copy of the survey results to the participant.

Each of these variations in the introduction is a distinct explanatory variable that might influence the outcome, which in this case is the completion of interviews. By understanding these variables, researchers can assess which introductions are more effective in preventing refusals.

Response Variables

A response variable, also referred to as the dependent variable, is what researchers measure in an experiment and what is expected to change due to variations in the explanatory variables. In this telephone survey study, the response variable is the completion status of the interview.
This means that the primary outcome of interest is whether the interviewee agrees to complete the survey after the introduction.
The objective of the research is to detect any patterns or differences in interview completion rates based on the introductory method used. This allows researchers to identify which strategies are most successful in lowering refusal rates.

Experimental Units

Experimental units are the individuals or objects to which the different treatments are assigned. In this exercise, the experimental units are the households that were randomly selected to receive the survey phone calls.
Each household represents an independent unit exposed to one of the possible introduction strategies.
By focusing on households as units, the study can generalize its findings to a broader population, examining how different introduction techniques might work across varying demographic groups or regions. The random selection of households ensures that the sample is representative, which supports the validity of the experiment's conclusions.

Treatments

Treatments refer to the various conditions or combinations of explanatory variables applied to the experimental units. In this research, the treatments are the different combinations of introduction strategies used during phone calls.

• These combinations could involve mentioning just the interviewer's name, only the university, both names, or neither.
• Another aspect of the treatment is whether the interviewer offers to send survey results.

By analyzing the effects of each treatment, researchers aim to conclude which specific combination of these variables leads to the highest interview completion rate. Employing different treatments allows for a detailed assessment of how each factor contributes to reducing refusals. This structured approach helps isolate and understand the impact of each element within the overall experiment.