1 EDHD 306 Spring 2014 Final Exam Study Guide Experimental design o Experimental control and randomization Ways to eliminate confounding influence from other variables Experimental Control Known as the control group Similar to population between tested but no change is implemented Randomization Randomly organizing groups o Confounding variables Variables that vary along with independent variable Other variables that can effect the result o Internal validity How well a study is done Avoids confounding variables High internal validity increases confidence in researchers explanation of problem o Basic experiments Posttest only design Introduce the independent variable Obtain 2 equivalent groups of participants Measure the dependent variable Ex only measure how well people drive after variable is manipulated Pretest posttest design Almost identical to posttest only A pretest is given prior to any treatment or experimental manipulation Ex test driving ability before variable manipulated then again after o Advantages and disadvantages of having a pretest variable is manipulated Advantages Assess equivalency of groups with small sample size Can use to select participants for study mortality Disadvantages Sensitize participants to what is being studied Reduce external validity Time consuming o Assigning participants to conditions Independent groups Randomly assign to only one level of the independent variable 2 Random assignment prevents systematic biases Repeated measures Assign to all levels of independent variable The same individuals participate in all conditions at different points in time Advantages and disadvantages o Advantages Fewer research participants needed Everyone participates in both conditions so they are equivalent o Disadvantages dependent variable o Types of order effects Order of presenting the treatments may affect the Practice effect improvement in performance as a result of repeated practice with task Fatigue effect deterioration in performance as the participant becomes tired bored or distracted Carryover effect the effect of the first treatment carries over to influence the response to the second treatment Counterbalancing o For repeated measures o All possible orders of presentation are included in the Matched pairs experiment First match on a participant characteristic and randomly assign to only one level of the independent variable People are matched on a participant characteristic and then each person from the pair group is assigned to either one condition or the other Goal achieve the same equivalency within groups that you obtain in a repeated measures design without actually having the same participants in both conditions Helpful with small samples sizes o Manipulations Independent variables Straightforward manipulations verbal or visual material Presented directly to participants Staged manipulations Researchers manipulate the independent variable using written Events that occur during the experiment are staged in order to manipulate the independent variable Employ confederate Confederates Strength of the manipulation 3 The differences between the groups should be maximized o Dependent variables Types of measures Self report participants provide information about themselves Behavioral measures observations of participants behaviors Physiological measures recordings of bodily responses Sensitivity relates to the test s ability to identify a condition Sensitivity correctly Ceiling effects The level at which an independent variable no longer has an effect on a dependent variable The level above which variance in an independent variable is no longer measured or estimated Floor effects The floor effect is a statistical phenomenon in which most data points fall in the very low range of possible values bottom out on the floor of the measure The floor effect is often seen in assessment when a test is too challenging for a given target population o Participant expectations Demand characteristics Can be controlled for minimized by o Using deception o Using filler items in a questionnaire o Simply asking participants about their perceptions of the purpose of the research o Experimenter expectations Expectancy effects Observer researchers cognitive bias causes then to unconsciously influence the participants of an experiment Subject the research subject expects a given result and therefore unconsciously affects the outcome Clever Hans o A form of involuntary and unconscious cuing Teacher expectancy self fulfilling prophecy o Perception of student s abilities Solutions to expectancy problem Well trained experimenters Simultaneous conditions Use of experimenters unfamiliar with the hypothesis o Manipulation checks Can show whether your manipulation was effective or not Gives information about non significant results o Making experiments more complex Increasing the levels groups conditions of the independent variable 4 Can uncover curvilinear relationships Increasing the number of independent variables Increasing the number of dependent variables o Factorial designs More than one independent variable Types of designs 2x2 2x3 2x2x2 o Two independent variables each with two levels o Three independent variables with two levels each o Four independent variables with two levels each o Two independent variables one with three levels one with 2 x 2 2 x 2 x 2 2 x 2 x 2 x 2 3 x 2 3 x 3 two levels o Two independent variables with three levels each Main effects The effect of each independent variable taken by itself The overall relationship between each independent variable and the dependent variable Interactions Interactions are harder to find in data so we look for them using statistical tests and by graphing the levels of both variables Moderator variables A variable that affects the direction or strength of the relation between two variables Moderating variables can occur in almost any study and are not unique to experimental or factorial design Other research designs o Correlational Design variables o Program evaluation Non experimental Simply looking at the relationship or correlation between measured Research on programs that are implemented to achieve positive effect on a group of individuals 5 types of evaluations Needs assessment Program theory assessment Process evaluation Outcome evaluation Efficiency assessment Example bullying district Needs assessment is there a problem with bullying in out school 5 Program theory assessment does our program target the