Statistics Chapter Two

Experiments and Observational Studies

Steps to plan a Statistical Study

First identify the individuals, then specify the variables, then determine if you will use an entire population/representative sample, then if we use a sample decide on the sampling method, then lastly collect the data this can be done through many different methods like observing, recording, or even doing like a sample survey.

Observational study

The researchers observe, record, and even do a sample survey in order to collect information on individuals. But they intentionally do not try to change any other type of conditions.

Experiments

Actively try to produce data. The researchers intentionally intervene by imposing some treatment on individuals in order to observe its effects. An example is like drinking gatorade.

Explanatory variable

The type of variable that may explain the influence or change in another type of variable.

Response variable

Is the variable that is being measured as the outcome or result. For example like the running time.

Placebo Effect

When a subject ends up receiving no treatment but incorrectly believes that they are in fact receiving treatment and responds favorably.

Subjects

The individuals in an experiment that are being studied.

Lurking variable

A variable that has an important effect on the relationship among the variables in a study but is not one of the explanatory variables studied.

Cofounding variable

When the effects on a response variable cannot be distinguished from each other. The confounded variables may either be explanatory variables or lurking variables.

In an experiment, how can experimenters produce more reliable results?

By using random assignment as well as the placebo effect.

Single-blind experiment

The subjects do not know which treatment that they are receiving.

Double blind experiment

Neither the subjects as well as the researchers who work with them end up knowing which treatment that each subject ends up receiving.

Statistically significant

With certain techniques in place, researchers can determine if their study is statistically significant. Overall meaning that the differences observed between groups are large enough that they would be unlikely to occur just by chance alone.