1 / 8

Collecting Data

Collecting Data. Observational Study. In an observational study researchers don’t assign choices, they simply observe them. Observational studies are valuable for discovering trends and possible relationships .

zena
Télécharger la présentation

Collecting Data

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Collecting Data

  2. Observational Study • In an observational study researchers don’t assign choices, they simply observe them. • Observational studies are valuable for discovering trends and possible relationships. • However, it is not possible for observational studies to demonstrate a causal relationship.

  3. Experiment • An experiment is a study that allows you to prove cause-and-effect relationship. • They manipulate factor levels to create treatments. • They randomly assign subjects to these treatment levels. • They compare the responses of the subject groups across treatment levels.

  4. Experiment • An experiment must have at least one explanatory variable, called a factor, to manipulate, and at least one response variable to measure. • A treatment is a combination of specific levels from all the factors that a subject receives.

  5. The 3 Principles of Experimental Design • Control to make sure all conditions are as similar as possible for all treatment groups. • Randomize to equalize the effects of unknown or uncontrollable sources of variation. No experiment is valid without randomization. • Replicate and apple the treatments to a number of subjects.

  6. Control • A group who receive no treatment is called the control group. • This gives a baseline to compare treatment groups. • To further control unseen variables, subjects in both the control and treatment groups are not allowed to know which group they are in. This is called blinding.

  7. Blinding • You may have heard of a placebo effect. • This is when people think they are getting a treatment and claim to have a change. • To control this, a placebo is used in an experiment. • This is a false treatment. Usually this is a fake pill. It is the easiest way to blind a subject.

  8. Blinding • When those receiving the false treatment or those doing the evaluating do not know who received what treatment we call it single-blind. • When both those receiving the treatment and those doing the evaluating are unaware of who received each treatment is called double-blind.

More Related