Psyc 2020 Hesse Fall 2009 Unit 5 Exam Name: ______________________________ ID#: ___ ___ ___ ___ Exam + Class + Bonus = 38 12 6 50 (1) Write your answers in the space provided under each question. (2) Read the questions carefully and be sure to answer each as asked. 1) College students participated in a driving simulation study to investigate night-driving reactions as a function of alcohol consumption and road conditions. Participants were divided into four groups that drank "cocktails" containing either no alcohol, 2 ounces of alcohol, 4 ounces of alcohol, or 6 ounces of alcohol. After 30 minutes, they began the driving simulation test. Each participant simulated a one minute drive on a straight road, a road with gentle curves, and a road with many sharp curves. Each simulated road contained the same road hazards. The number of accidents was measured. a) As described, is this an independent groups, repeated measures or mixed factorial design? ____ A mixed factorial design_ (1 pt) b) Why? (1 pt) The independent variable of alcohol amount (4 levels) is an independent groups variable and the independent variable of road conditions (3 levels) is a repeated measures variable so together they make a 4X3 mixed factorial design (a mixed factorial design has both independent groups and repeated measures parts to it). c) Name the independent variables and their levels and the dependent variable in this experiment. (3 pts) Two independent variables: Alcohol level with 4 levels (0,2,4,6 oz) and Road conditions with 3 levels (straight, gentle curves, sharp curves). The dependent variable is the number of accidents. d) Using an independent groups design this experiment would have how many groups?_12_ (1 pt) 2) Define the following terms as was done on the lecture slides from class. Do not refer to the numbers on the inside or outside of a matrix as part of your definition!) a) The “main effects” in a factorial experiment? (2 pts) The effect each independent variable on the dependent variable averaged across all levels of the other independent variables. b) The “interaction effects” in a factorial experiment? (2 pts) The individual effects of each level of an independent variable at each level of the other independent variables.. 3) What is the name of the design diagramed below? (1 pt) _____Pre-test Post-test design______ R means? ______Random assignment of participants to groups______ O1 means? ______Pre-test measurement of the dependent variable___ X means? __Introduction of the independent variable manipulation (2 pts) O2 means? ____Post-test measurement of the dependent variable____ R O1 X O2 R O1 O2Psyc 2020 Hesse Fall 2009 Unit 5 Exam 4) Place the numbers in the proper matrix cells below, A1B1=30 A1B2=30, A2B1=20, A2B2=40. Next graph these 4 data points. Label correctly the two lines connecting points above A1 & A2 as B1 and B2. (2 pts for an accurate matrix and graph) B1 B2 A1 A2 A1 A2 Using the data and figures above: a) Is there a main effect of A? (1 pt) ___NO___How do you know? (1 pt) Both means (A1 and A2 are equal at 30) b) Is there a main effect of B? (1 pt) __YES____How do you know? (1 pt) B1 mean is 25 and B2 mean is 35, they are unequal and therefore B2 had a greater effect than B1. c) Is there an A X B interaction effect? (1 pt) __YES_____? How do you know? (1 pt) The graphed lines are not parallel they cross which indicates that the effect of one variable is different given the level of the other variable. 5) Describe (or use a diagram like in question #3) the Solomon four-group design. (2 pts) a) Explain how this design assesses the impact of pre-testing on the dependent variable? (3 pts) Because both the control group and the experimental group each have a group that gets a pre-test and one that doesn’t. If you see a difference between the two groups in the control condition (let’s say the group that got the pre-test scored higher than the group that got the post-test only) we can say the higher score was due to the pre-test sensitizing the participants to the measurements. There were no other differences between the groups. If the two post-test measurements in the experimental group are also different (and the post-test scores are higher in the pre-tested group) we have confirmed the findings on pre-testing from the control groups. If the control group has equal post-test means but the experimental group has unequal post-test means we can say that the effects of the IV were influenced by the pre-testing. The overall effects of the IV are assessed by the differences between the averaged post-test scores of the control group compared to the experimental group. This design is interesting because it has pre-testing control groups inside both the experimental group and the control group. 30 30 20 40 40 30 20 10 B1 B2 Control R O2 R O1 O2 Experimental R X O2 R O1 X O2Psyc 2020 Hesse Fall 2009 Unit 5 Exam 6) Subdivide this box into a 3X2X4 matrix and correctly label the variables A1, A2, A3 & B1, B2 & C1, C2, C3, and C4 in the margins of the matrix. Put the letter X in cell A1B1C3 and the letter Y in cell A3B2C1. (6 pts) There should be 24 cells in the matrix. A1 A2 A3 B1 B2 B1 B2 B1 B2 C1 Y C2 C3 X C4 a) Describe how you would use a repeated measures design to study the effects of three levels of background noise on reading comprehension with 60 participants. (2 pts) In a repeated measures design, all participants get all levels of the independent variable. So in this study all 60 participants would first read a paragraph with no background noise and take a comprehension test over it (level 1), next they would read a comparable paragraph with a moderate level of background noise (say 15 db of noise) and take a comprehension test over it and finally they would read a third paragraph comparable to the first two with a high level of background noise (say 35 db of noise) and take a comprehension test over it. We would average the scores of all participants in each group and compare the three averages to see which condition produced the highest or lowest score. b) Since order effects are a major weakness of the repeated measures design, name and describe two that might be found in