# Whether the given study depicts an observational study or a designed experiment and to identify the response variable. The study is conducted to compare the battery lives of a brand-name battery and a generic plain-label battery in digital cameras. For this purpose, 30 digital cameras are randomly selected and divided into 2 groups, one of the groups uses the brand-name battery while the other one uses the generic plain-label battery. In both the cameras, pictures are taken under identical conditions by keeping all variables, except the battery-type, in control.

This article aims to determine whether the statement is an example of an observational study or a designed experiment.

Designed experiment is a sequence of runs or tests in which you purposefully change input variables simultaneously and observe the responses. In industry, designed experiments can systematically investigate product variables that affect product quality. After you identify process conditions and product components that affect product quality, you can direct improvement efforts to improve product manufacturability, reliability, quality, and field performance.

For example, you work at an offset printing company where some customers have complained about unattached pages from the bindings of their books. You suspect several factors: cooling time, glue temperature, and paper type. You want to determine which elements or combinations of factors significantly affect the effectiveness of your company’s bonding technique. When you make a designed experiment, Minitab automatically randomizes the order in which the design is run and displays the design in your worksheet. Run order is an ordered sequence of factor combinations. You can use worksheet to record your answers as you experiment.

Observational study is typically used to answer a research question based purely on what researcher observes. There is no interference or manipulation of research subjects and no control and treatment groups. These studies are often qualitative and can be used for exploratory and explanatory research purposes.

Observational study: An observational study measures the values of a variable without influencing the importance of the response variables and the explanatory variables. Thus, in an observational study, researchers can observe the behavior of individuals without affecting the outcome of that study.

Designed experiment: In a designed experimental study, researchers assign individuals to a particular study group and intentionally change the values of the explanatory variable, after which the importance of the response variable is recorded for each group.

The $2$ types of batteries are $2$ treatments given to cameras (individuals) that are influenced by purpose, under a controlled setting, and battery life is recorded for each individual. So the study is a designed experiment.

Response Variables: The focus of the question in an experimental study is the response variable, where the interest is to make measurements and draw conclusions about it. The experiment compares the “lifetimes” of the two types of batteries measured in the investigation. So, battery life is a response variable.

## Numerical Result

The study given in the question is a designed example.

## Example

Whether the given study depicts an observational study or a designed experiment, people are screened for a specific medical condition, such as cancer, to identify the response variable.

Solution

Observational studies are those where researchers observe effect of a risk factor, treatment, or other intervention. Cohort studies and case-control studies are two types of observational studies.

A designed experiment is a sequence of runs or tests in which you purposefully change input variables simultaneously and observe responses. In industry, designed experiments is used to investigate process or product variables that affect product quality systematically.

The given statement is an example of an observational study.

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