Chapter 12 Conducting & Reading Research Baumgartner et al Chapter 13 Inferential Data Analysis

Chapter 12 Conducting & Reading Research Baumgartner et al Review of statistical tests One sample t test Two independent samples t test Two dependent samples t test ANOVA One-way Chi-Square Test Two-way Chi-Square Test

Chapter 12 Conducting & Reading Research Baumgartner et al Example 1

Chapter 12 Conducting & Reading Research Baumgartner et al Ferguson, Douglas C., Chuck E. Harp, Paul A. Opler, Richard S. Peigler, Michael Pogue, Jerry A. Powell, and Michael J. Smith Moths of North America. Jamestown, ND: Northern Prairie Wildlife Research Center Home Page. (Version 12DEC2003). Why do butterflies and moths have eye spots?

Chapter 12 Conducting & Reading Research Baumgartner et al Research hypothesis: Eye spots are a defense against moth-eating birds. Experiment: –Test effect of exposure to eye-spot patterns on behavior of moth-eating birds. Sample: –N=16 moth-eating birds

Chapter 12 Conducting & Reading Research Baumgartner et al Method: –Test in a 2 chamber enclosure, separated by a partition with a doorway. Birds are free to roam from chamber to chamber. –Chamber 1 has plain walls, chamber 2 has eye-spot patterns painted on the walls. –Birds are tested one-at-a-time by placing in the doorway in the center. –Each bird left in box for 60 minutes. –Amount of time spent in each chamber is recorded.

Chapter 12 Conducting & Reading Research Baumgartner et al What are the independent and dependent variables? Independent: Chamber selected Dependent: Amount of time spent there.

Chapter 12 Conducting & Reading Research Baumgartner et al What statistical test do we use? One sample t-test H 0 : Birds show no preference for either chamber –H 0 : µ = 30 (for room with spots) H A : Eye patterns affect behavior, but will they show avoidance or attraction? –H A : µ ne 30 (2-tailed test) Go to SPSS file to analyze

Chapter 12 Conducting & Reading Research Baumgartner et al Alternative hypotheses, controls? Lighting in chambers Time of day Motivation (food deprivation) Different or same species?

Chapter 12 Conducting & Reading Research Baumgartner et al Example 2

Chapter 12 Conducting & Reading Research Baumgartner et al Pharmacology example Assess effectiveness of new drug by noting concentration in blood and/or urine certain time points after giving Want to compare two types of aspirin (A and B)

Chapter 12 Conducting & Reading Research Baumgartner et al Experiment: –Test clearance of each type of aspirin one hour after it is given Sample: –N=10 subjects Research hypothesis: There is no difference in the effectiveness of the two types of aspirin

Chapter 12 Conducting & Reading Research Baumgartner et al Method: –Randomly assign half the subjects to receive aspirin A first and the other half to receive aspirin B –Give same dosage of assigned aspirin to each subject –Test amount of aspirin in urine 1 hour later –One week later, after aspirin has cleared system, test each subject with the other aspirin

Chapter 12 Conducting & Reading Research Baumgartner et al What are the independent and dependent variables? Independent: –Type of aspirin Dependent: –Amount of aspirin in urine 1-hour later

Chapter 12 Conducting & Reading Research Baumgartner et al What statistical test do we use? Two dependent samples sample t-test H 0 : No difference in amount of drug in system –H 0 : µ A - µ B = 0 H A : There is a difference in amount of drug in system –H A : µ A - µ B ne 0 (2-tailed test) Go to SPSS file to analyze

Chapter 12 Conducting & Reading Research Baumgartner et al Alternative hypotheses, controls? Differences in subjects body composition Differences in subjects eating/drinking habits Genetic differences in pharmacological response to aspirin

Chapter 12 Conducting & Reading Research Baumgartner et al Example 3

Chapter 12 Conducting & Reading Research Baumgartner et al Duncker’s Candle Problem 2 volunteers to leave room –Haven’t had class in cognitive psychology

Chapter 12 Conducting & Reading Research Baumgartner et al Experiment: –Test length of time it takes subjects to solve the problem. Sample: –N=20 subjects Research hypothesis: It will take longer for subjects who are given tacks in the box to solve the problem.

Chapter 12 Conducting & Reading Research Baumgartner et al Method: –Randomly assign half the subjects to get tacks in the box and half to get tacks out of the box –Measure how much time it takes each subject to solve the problem

Chapter 12 Conducting & Reading Research Baumgartner et al What are the independent and dependent variables? Independent: –Location of tacks Dependent: –Amount of time to solve problem

Chapter 12 Conducting & Reading Research Baumgartner et al What statistical test do we use? Two independent samples t-test H 0 : No difference between people who get tacks in box or out of box –H 0 : µ 1 - µ 2 = 0 H A : The group who gets the tacks in the box takes more time to solve –H A : µ 1 - µ 2 > 0 (1-tailed test) Go to SPSS file to analyze

Chapter 12 Conducting & Reading Research Baumgartner et al Alternative hypotheses, controls? Attitude of researcher as box, tacks, candle are presented Differences in subjects educational background/IQ Differences in subjects age/gender