Does caffeine improve exam performance? Suppose all students in the 8:30 section of acourse are given a "treatment" (two cups of coffee) and all students in the 9:30 section arenot permitted to have any caffeine before a mid-term exam.Unfortunately, any systematic difference between the two sections on the exam might bedue to the fact that the 8:30 and 9:30 classes have different instructors.This is an example of ...O abias.Obconfounding.placebo effect.observational study.O cd

Ans: B) Confounding Effect It is not due to caffeine it is due to exam performance. It happens due…

Answered: Does caffeine improve exam performance?…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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An SAT prep course claims to improve the test score of students. The table below shows the scores for seven students the first two times they took the verbal SAT. Before taking the SAT for the second time, each student took a course to try to improve his or her verbal SAT scores. Do these results support the claim that the SAT prep course improves the students' verbal SAT scores? Let d = (verbal SAT scores prior to taking the prep course)-(verbal SAT scores after taking the prep course). Use a significance level of a = 0.01 for the test. Assume that the verbal SAT scores are normally distributed for the population of students both before and after taking the SAT prep course. 1 234567 520 570 540 380 370 490 450 Student Score on first SAT Score on second SAT 540 600 610 470 410 510 480 Step 1 of 5: State the null and alternative hypotheses for the test. Answer 0 Ho: Md 0 Ha Ma IA IV V A || < = Copy Data Tables Keypad Keyboard Shortcuts
A certain affects virus 0.8% of the population. A test used to detect the virus in a person is positive 88% of the time if the person has the virus (true positive) and 13% of the time if the person does not have the virus (false postive). Fill out the remainder of the following table and use it to answer the two questions below. (enter answer with no commas, i.e. as 1000 not 1,000.) Infected Not Infected Total Positive Test [a] [b] [c] Negative Test [d] [e] [f] Total 800 99,200 100,000 i) Find the probability that a person has the virus given that they have tested positive. (Round your answer to the nearest tenth of a percent and do not include a percent sign.)[g]_______ % ii) Find the probability that a person does not have the virus given that they test negative. (Round your answer to the nearest tenth of a percent and do not include a percent sign.)[h]________ %
ch 15 end. 5: A marketing research firm wishes to study the relationship between wine consumption and whether a person likes to watch professional tennis on television. One hundred randomly selected people are asked whether they drink wine and whether they watch tennis. The following results are obtained:
3. A mathematics placement test is given to all entering freshmen at a small college. A student who receives a grade below 35 is denied admission to the regular mathematics course and placed in a remedial class. The placement test scores and the final grades for 20 students who took the regular course were recorded as follows: Placement Test Course Grade | Placement Test | Course Grade 50 53 90 54 35 35 41 80 60 91 61 48 40 56 60 71 55 68 60 71 65 36 40 47 35 11 55 53 60 70 50 68 90 79 65 57 35 59 50 79 (a) Plot a scatter diagram. (b) Find the equation of the regression line to predict course grades from placement test scores. (c) Graph the line on the scatter diagram (d) If 60 is the minimum passing grade, below which placement test score should students in the future be denied admission to this course?
1. In a psychological study of distance perception, introductory psychology class volunteers were given either 5 or 10 extra credit points depending on their level of participation in the experiment. They walked along paths laid out along hallways in the psychology building, and were asked to judge the distance they had walked. Each path distance was between 100 and 200 feet in length, and contained from two to seven 90 degree turns. The investigators also kept track of class standing (freshman, sophomore, junior, or senior) of each participant. For each of the variables in the study, determine whether it is qualitative or quantitative. For each quantitative variable, determine whether it is discrete or continuous. For each qualitative variable, determine whether it is nominal or ordinal. [4 pts.] a. The true length of the path b. The amount of credit given to volunteers c. Class standing d. The number of 90 degrees turns 2. In a survey of exercise habits, 1500 national adults were…
B7
Suppose you wish to find out the answer to the age-old question, "Do people prefer Cola 1 or Cola 27?”You conduct a bind taste test in which individuals are randomly asked to drink one of the colas first, followed by the other cola, and then asked to disclose which drink they prefer. Results of your taste test indicate that 51 of 100 individuals prefer Cola 2. Complete parts a through c.
14. A researcher is conducting a case study of a famous artist. She interviewed the artist, the artist's friends, and the artist's colleagues. She is then going to describe the artist using his own words (and the words of his friends and colleagues), while looking for some themes she finds in their descriptions. What type of research is this? Qualitative Quantitative

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