Instructions

Assignment 3 consists of three problems covering the topics of ANOVA and correlation/regression from weeks 8 through 11.

Each problem is on a separate sheet that can be accessed by clicking the tabs below.

Provide your answer to each problem on the sheet associated with that problem (i.e., answer to Problem 1 on Problem 1 sheet, answer to Problem 2 on Problem 2 answer sheet, etc.)

For hypothesis testing questions, use the four-step procedure outlined in class and assume α = 0.05, unless instructed to do otherwise in the problem. For all problems, provide a conclusion for each question in everyday English.

For ANOVA question(s), include a post-hoc test. For correlation questions, include a scatterplot that incorporates a regression line.

To obtain full credit, show any calculations that are required.

I will post a sample assignment 3 (including answers). Use this sample assignment to aid completion of Assignment 3.

Problem 1

A working memory test was administered to 31 participants. Low scores indicate low working memory capacity whereas high scores indicate high working memory capacity. The same participants were also given a difficult text comprehension task, with low scores corresponding to poor comprehension and high scores corresponding to good comprehension. The scores for each participant's working memory performance and comprehension task performance are shown on the right. Is there a relationship between working memory capacity and comprehension performance?

Problem 2

Speech perception researchers have found that the ability to discriminate between two nonnative speech categories depends on the time period - the interstimulus interval (ISI) - separating the two sounds, with the general pattern of results showing improved discrimination as the ISI decreases. A researcher does an experiment in which she tests two sounds from a language not previously examined to see if the results are consistent with past research. She recruited four groups of listeners and tested each group with stimuli from one ISI condition. The results are shown at right (the dependent variable is percentage correct based on 100 discrimination trials). Is there a difference in discrimination accuracy between the different ISI conditions for the two speech sounds?

Problem 3

A human-computer interaction researcher wanted to know how device size affected the enjoyment level when people played video games. He tested the same game on three different devices, an iPhone, an iPad, and a 27 inch monitor. Each participant played on all three devices; the order of playing was counterbalanced across participants. Enjoyment was measured using a rating scale that ranged from 1 ("I didn't enjoy the game at all") to 5 ("I really enjoyed the game"). The ratings are presented in the table on the right. Did the players' enjoyment vary as a function of device size?