Concept explainers
The paper “If It’s Hard to Read, It’s Hard to Do” (Psychological Science [2008]: 986–988) described an interesting study of how people perceive the effort required to do certain tasks. Each of 20 students was randomly assigned to one of two groups. One group was given instructions for an exercise routine that were printed in an easy-to-read font (Arial). The other group received the same set of instructions, but printed in a font that is considered difficult to read (Brush).
After reading the instructions, subjects estimated the time (in minutes) they thought it would take to complete the exercise routine. Summary statistics are given below.
The authors of the paper used these data to carry out a two-sample t test, and concluded that at the 0.10 significance level, there was convincing evidence that the
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Chapter 11 Solutions
Introduction to Statistics and Data Analysis
- What is meant by the sample space of an experiment?arrow_forwardWhat is a sample space?arrow_forwardIn a case-control study researchers investigated whether there was an association between living near a high-hazard dump site versus a low-hazard dump site and risk of having a low birth weight child. The study found that in a group of women living near a high-hazard dump site while pregnant there were 181 low birth weight children and 4268 normal birth weight children. Corresponding numbers for women living near a low-hazard dump site were 126 and 4236, respectively. a. Formulate the null and alternative hypotheses. b. Estimate the odds ratio and 95% confidence interval. Interpret the result and say what the interval tells us about statistical significance. 20.arrow_forward
- Craik & Tulving ran an experiment to determine how depth of processing during study affects memory. In the study phase, 12 participants made judgments about words. In one block of trials (the visual condition) they indicated whether the words were written in upper case or lower case; in another block of trials (the auditory condition) they indicated whether the words contained an "ee" sound; in another block of trials (the meaning condition) they indicated whether the meaning of the words was pleasant or unpleasant. There were 12 words in each block. After completing the study phase, participants were asked to write down all the words they could remember. Here are the data: Mean Visual 3.5 Auditory 4.5 Meaning 6.0 Standard Deviation 1.5 1.6 1.9 Compared to the within-subjects design, the between-subjects design (select all that apply) Oa. Would have less statistical power O b. Would be less prone to experimenter bias O c. Would be less prone to order effects Od. Would have better…arrow_forwardDo d, e and f part of the question thank youarrow_forwardA study was conducted to determine whether big-city and small-town dwellers differed in their helpfulness to strangers. In the study, the investigators rang the doorbells of strangers living in Toronto or small towns in the vicinity. They explained they had misplaced the address of a friend living in the neighborhood and asked to use the phone. The following data show the number of individuals who admitted or did not admit the strangers (the investigators) into their homes: Admitted strangersinto their home Did not admit strangersinto their home Big-city dweller 60 90 Small-town dweller 70 30 Conduct a chi-squared test to examine whether big-city dwellers differ in their helpfulness to strangers. Which of the following is/are true about the result of the test? A. The obtained chi-squared test statistic is 21.6346. B. The obtained pp-value is approximately 0. C. The obtained chi-squared test statistic is 8.450. D. The obtained…arrow_forward
- A researcher is interested in whether people will show different amounts of cognitive dissonance when viewing images of animals in distress vs. images of humans in distress. The researcher collects data from N = 12 people and randomly assigns six people to an Animal Distress condition and six different people to a Human Distress condition. Participants were shown 20 images superimposed onto one of 4 color backgrounds (i.e., red, yellow, green, and blue) and were asked to report the color behind each image as quickly as possible using keys on a keyboard. Participants in the Animal Distress condition were shown 20 images of animals in distress and participants in the Human Distress condition were shown 20 images of humans in distress. Cognitive dissonance was measured using the number of errors made in identifying background colors. The data were as follows: Animal Distress: 8, 6, 7, 8, 5, 9 Human Distress: 3, 2, 4, 1, 2, 2arrow_forwardA psychologist studying the human factors of computer keyboards sets up an experiment to compare two different keyboard designs. He measures the number of words per minute typed by one group on Keyboard A and then he measures the number of words typed per minute by another group of people on Keyboard B. Use the data below to determine if the typing speeds on the two different keyboards are significantly different. Keyboard A (words per minute) 54, 62, 75, 59, 78, 64, 69, 72, 50, 73 Keyboard B (words per minute) 47, 51, 54, 62, 44, 51, 48, 65, 42, 44, 71, 68 Evaluate on a TI 83 calculatorarrow_forwardA report described teens' attitudes about traditional media, such as TV, movies, and newspapers. In a representative sample of American teenage girls, 42% said newspapers were boring. In a representative sample of American teenage boys, 45% said newspapers were boring. Sample sizes were not given in the report. A button hyperlink to the SALT program that reads: Use SALT. (a) Suppose that the percentages reported had been based on a sample of 50 girls and 40 boys. Is there convincing evidence that the proportion of those who think that newspapers are boring is different for teenage girls and boys? Carry out a hypothesis test using ? = 0.05. (Use pgirls − pboys.) Find the test statistic. (Round your answer to two decimal places.) z = Find the P-value. (Round your answer to four decimal places.) P-value = State your conclusion. Reject H0. We do not have convincing evidence that the proportion of girls who say that newspapers are boring is different from the proportion of boys who…arrow_forward
- A Doctor is interested in the proportion of Lyon county residents who were infected with covid-19 virus. There were 425 covid-19 cases reported among 25474 residents in Lyon county. a. What is a statistics in this experiment? b. What variables should pollster collect in this experiment?arrow_forwardA researcher is interested in whether completing a six-week speed-reading course designed for sighted readers affects reading speed among blind Braille readers. She has blind adults complete a reading speed test before and after a six-week speed-reading course. The researcher randomly selects a sample of 50 blind Braille readers who, at the beginning of the study, scored an average of 261 words per minute on the reading speed test. After the speed-reading course, the blind Braille readers scored an average of 7 words per minute higher. The standard deviation of the difference scores was 21. Since the sample size is larger than 30, the researcher can assume that the sampling distribution of MD is normal. She uses a repeated-measures t test to test that the mean difference is zero, and she describes the results as follows: After the speed-reading course, the Braille reading speed among blind Braille readers is significantly different than before taking the course, t(49) = 2.36, p =…arrow_forwardA teacher is interested in the effect of a study session on quiz performance. Two different classes receive a pretest and a posttest. Thus, the teacher records the following four set of scores: Class 1 pretest = (5, 8, 9, 10, 12, 12, 14) Class 1 posttest = (18, 18, 20, 20, 20, 20, 24) Class 2 pretest = (2, 4, 8, 12, 12, 12, 20) Class 2 posttest = (10, 12, 20, 21, 21, 28, 28) For each of for sets of scores above, calculate the sample mean and standard deviation. In which class is the effect of the study session most obvious in the pattern of data?arrow_forward
- Holt Mcdougal Larson Pre-algebra: Student Edition...AlgebraISBN:9780547587776Author:HOLT MCDOUGALPublisher:HOLT MCDOUGALGlencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw HillCollege Algebra (MindTap Course List)AlgebraISBN:9781305652231Author:R. David Gustafson, Jeff HughesPublisher:Cengage Learning