Foundations of Sociological Inquiry Experiments

Today’s Objectives  What is an Experiment?  Selecting Subjects  An Illustration of Experimentation  Strengths and Weaknesses of the Experimental Method  Questions?

Experiments  Experiments involve:  Taking action  Observing consequences of that action

Experiments  Experiments involve:  Taking action  Observing consequences of that action  Well-suited for projects involving limited and well- defined concepts and propositions:  Hypothesis testing  Better suited for explanatory than descriptive  Small group interaction

Major Components: 1. Independent and Dependent Variables 2. Pre-testing and Post-testing 3. Experimental and Control Groups

Major Components: 1. Independent and Dependent Variables  Independent – takes the form of a stimulus (present or absent), cause  Dependent - effect 2. Pre-testing and Post-testing 3. Experimental and Control Groups

Major Components: 1. Independent and Dependent Variables 2. Pre-testing and Post-testing  Pre-testing – the measurement of a dependent variable along subjects.  Post-testing – the measurement of a dependent variable among subjects after they have been exposed to an independent variable. 3. Experimental and Control Groups

Major Components: 1. Independent and Dependent Variables 2. Pre-testing and Post-testing 3. Experimental and Control Groups  Experimental Group – a group of subjects to whom an experimental stimulus is administered.  Control Group – a group of subjects to whom no experimental stimulus is administered and who should resemble the experimental group in all other respects.

In the simplest experimental design, subjects are measured in terms of a/n _____ variable exposed to a/n _____ variable. 1. pre-test;post-test 2. post-test;pre-test 3. dependent;independent 4. independent;dependent

_____ groups are groups of subjects to whom an experimental stimulus is administered. 1. control 2. experimental 3. purposive 4. pre-test

_____ is a technique for assigning experimental subjects to experimental and control groups randomly. 1. Non-probability analysis 2. Matching 3. Controlling 4. Randomization

Selecting Subjects  Convenience/Cost  Generalizability

Professor Pettit examines how sending an to students affects students assessment of a course. Pettit compares evaluations of students who received an declaring her devotion to student learning with those who didn’t receive an . She is conducting: 1. an experiment 2. deception 3. no harm to participants 4. qualitative research 5. ethnography

Dear Students, Thank you for being a part of Sociology 300 this quarter. I am very excited about the class and very interested in doing what I can to enhance the learning environment. My primarily goal is to help you learn the material. To that end, the TAs and I will be soliciting suggestions from you over the next couple of weeks for ideas for in-class activities to enhance your learning. We've got a few ideas of our own, but we are eager to hear your ideas too. I will be available in my office hours this Tuesday from 3-5pm (Savery 224) to meet with you and hear your suggestions. I will also hold extra office hours this week on Friday from 3-5pm for this purpose. The TA's will be holding office hours as well to discuss these issues and any others arising in Sociology 300. We look forward to hearing from you! We are eager to work with you to enhance the learning environment for Sociology 300. Please don't hesitate to contact me if you have any questions or if there is anything I can do to help. All best, Becky

Professor Pettit did an experiment on her students in a classroom. She measured their views about the course on the first week, randomly assigned half of them to receive an offer for extra help on the second week, and measured their views about the course on the third week. Measuring the student’s views on the third week is the 1. independent variable. 2. posttest. 3. pretest. 4. experimental group. 5. control variable

Professor Pettit did an experiment on her students in a classroom. She measured their views about the course on the first week, randomly assigned half of them to receive an offer for extra help on the second week, and measured their views about the course on the third week. The half of the students who did not receive an offer of extra help are known as the 1. independent variable. 2. experimental group. 3. pretest. 4. control group. 5. posttest.

Professor Pettit did an experiment in class over the space of a few weeks to examine the effect of specific interventions on course evaluations. She randomly assigned students to the experimental and control groups and did a pretest and posttest. At the time of the posttest, several student realized that they received the same questions on the pretest, and used the same answers they had originally given on the pretest even though their evaluations may 1. history 2. maturation 3. instrumentation 4. testing 5. mortality have changed. Which source of internal invalidity does this example reflect?

Course evaluations (1=excellent; 6=very poor)

ExperimentalControl Course as a whole Course content Instructor overall Instructor's contribution Instructor's interest Amount learned

Do you think there was an experimental effect? 1. Yes 2. No

Do you think that there was an experimental effect?  Positive selection into sections AA, AB, AC  Small differences  How large is large?  Possible influential cases  More scores of fair and poor on course content and poor or very poor on instructor’s interest and amount learned in AD, AE, AF

Validity Issues in Experimental Research  Internal Validity – the possibility that conclusions drawn from experimental results may not accurately reflect what happened in the experiment itself.  Sources: history, maturation, testing, instrumentation, statistical regression, selection bias, experimental mortality, causal time order, diffusion or imitation of treatments, compensation, compensatory rivalry, demoralization  External Validity – the possibility that conclusions drawn from experimental results may not be generalizable to the “real” world

Strengths and Weaknesses of the Experimental Method  Strengths of Experimental Method  Isolation of experimental variable’s impact over time.  Replication  Weaknesses of Experimental Method  Artificiality of laboratory settings

Questions?