Mathias investigates whether studying in a group vs. alone is more effective in completing a task. He randomly assigns a sample of SHS students into two groups. One group has students studying together and the other group has students working alone. In this experiment, the independent variable is _________________ and the experimental design is _________________________ A. whether students studied alone or in a group; posttest only control group design B. whether students studied alone or in a group; pretest-posttest control group design. C. students' ratings of task difficulty; posttest only control group design D. students' ratings of task difficulty; pretest-posttest control group design

In a ________ study, both the researchers and the participants are unaware of the group assignments.

A university professor wants to study the benefits of weekly homework versus weekly testing through quizzes on the final performance of students. A class of 200 students are put into pairs where each pair includes a male and female student of equal academic ability. Then each half of a pair is assigned to the homework group and the other to the quiz group. which of the following best describes the design method used?Group of answer choicesblock randomisationlatin square designRepeated measures designMatched pairs design

1 Group workAnswer the following questions in small groups.Five sets of identical twins were selected at random from a population of identical twins. One child was selected at random from each pair to form an “experimental group.” These five children were sent to school. The other five children were kept at home as a control group. At the end of the school year the following IQ scores were obtained.Pair Experimental group Control group1 110 1122 125 1203 139 1284 142 1355 127 126Which of the tests that we have considered so far in DATA2002 can be applied here? Why might you use one instead of the other?If you were to proceed with a Wilcoxon signed rank test, calculate the test statistic.Under the null hypothesis of no difference in the mean IQ score between the experimental and control group, what is the expected value of the Wilcoxon signed rank test statistic?Let’s say we are testing a one sided alternative, i.e. the researchers hypothesised that the experimental group that were sent to school had higher IQs than the control group. If you had to guess which of the following p-values looks most reasonable for this example?0.00010.96630.09380.4367Don’t perform the test in R, just think about the observed test statistic, the expected test statistic and the sample size.

In an experiment, the group that receives the treatment the researchers want to study is known as the _____ group.Multiple choice question.experimentalcontrolplaceboquasi-experimental

A study is designed to test the effectiveness of a program to teach adolescents about nutrition. All research participants are randomly assigned to two groups, one which goes through the program and the other which does not. Both before and after the program, all participants take a test measuring knowledge of nutrition. What type of experimental design is this? A. posttest-only control group design B. pretest-posttest control group design C. 2 × 2 factorial design D. 2 × 4 factorial design