1 / 10

Experimental Design – how to design an experiment to test a hypothesis

Experimental Design – how to design an experiment to test a hypothesis. Biology I Honors. After Observing…. A problem or something that raises a question and… After doing background research and developing a hypothesis… You need to test the hypothesis

lisette
Download Presentation

Experimental Design – how to design an experiment to test a hypothesis

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. Experimental Design – how to design an experiment to test a hypothesis Biology I Honors

  2. After Observing… • A problem or something that raises a question and… • After doing background research and developing a hypothesis… • You need to test the hypothesis • There are several ways to do this. One of these is setting up a controlled experiment.

  3. Controlled Experiment • Designed to test a hypothesis • The elements of a controlled experiment are…

  4. Elements of a Controlled Experiment • Two or more set-ups of the experiment • Experimental treatment(s) • A set-up of the experiment that will have something “done to it” • May be more than 1 treatment (or set up) • Control treatment • A set-up of the experiment that will have NOTHING done to it • Standard of Comparison • Allows you to compare a “normal” situation to the experimental situation so that you can determine if your experimental variable is having an effect on results.

  5. Elements of a Controlled Experiment • Variables • Anything that is altered or that “varies” among set-ups (treatments) of an experiment. • Ideally, however, NOTHING varies between set-ups EXCEPT what you want to test. • Why? • If more than one variable is different between the set-ups, then there will be no way to know which variable is affecting results.

  6. Elements of a Controlled Experiment • Constants • All those POTENTIAL variables that are maintained the SAME for all set-ups of the experiment.

  7. Elements of a Controlled Experiment • Two Particularly Important Variables: • Independent (manipulated) Variable • Dependent (responding) Variable

  8. Elements of a Controlled Experiment • Independent Variable • The variable that is PURPOSEFULLY altered in an experimental treatment • There may be several “levels” to the IV • For example: Amount of Water given to plants • Amount of Water • 10 ml / day (“level 1” of the IV) • 25 ml / day (“level 2” of the IV) • 50 ml / day (“level 3” of the IV)

  9. Elements of a Controlled Experiment • Dependent Variable • The thing that is MEASURED as your experimental results • Example: Plant growth (in response to amount of water given)

  10. Trials • Multiple trials • Repetitions of an experiment • Do as many as possible • Typically 3 in class; or as many as there are lab groups (each lab group does a trial) • TRIALS DO NOTELIMINATE ERROR! • Mulitple trials DO REDUCE EFFECTS OF ERROR ON RESULTS!

More Related