1 / 11

Inferential Statistics

Inferential Statistics. Significance Testing Chapter 13. Important Terms. Null hypothesis Significance Probability of error (alpha levels) Confidence level Independent t test Dependent t test. Assumptions. Group studies – comparing experimental group with control group

kinsey
Download Presentation

Inferential Statistics

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. Inferential Statistics Significance Testing Chapter 13

  2. Important Terms • Null hypothesis • Significance • Probability of error (alpha levels) • Confidence level • Independent t test • Dependent t test

  3. Assumptions • Group studies – comparing experimental group with control group • Representative values to describe performance in both groups – mean and Sd • Probability of replication

  4. Comparing Mean Values • Mean values will be different • Caused by chance or caused by IV

  5. Null Hypothesis • Any observable difference between two mean values is simply due to chance • Significance testing either accepts or rejects null hypothesis • Acceptance means that observable difference was due to chance • Rejection means the IV caused the change

  6. Calculation • Independent t-test • Non independent t-test • See p.335

  7. Independent t-test • To determine significance between two independent groups, i.e., experimental group and control group • Experimental group receives IV; control group does not • Was the difference between experimental group mean and control group great enough to state significance?

  8. Significance • In essence, what is the likelihood that the group that receives the IV will score higher than the group who does not? • In essence, what is the probability that the group who receives the IV will not score higher than the group who does not? • In essence, how confident are you that the group who receives the IV will score higher than the group who does not?

  9. Alpha Levels • The symbol p means probability of error • An alpha level of .05 means probability of error is less than 5 out of 100 times that the IV group might not score higher • Or, 95% of the times the IV group will score higher • See p. 329

  10. Alpha levels (cont.) • An alpha level of .01 means that less than 1 out of 100 times the IV group might not score higher • Or, 99% of the times the IV group will score higher • What about an alpha level of .001?

  11. Non independent t-test • To determine significance between pre and post tests within one group • One group, two treatments • Examples

More Related