Think like a scientistsImagine you predict that it will take a salesclerk at a mall longer to help out a potential customer who is dressed insloppy clothes (untucked t-shirt and torn jeans) than a potential customer dressed in business attire. You run the studyand find support for your hypotheses, with the obtained value exceeding the critical value at the p < .05 level. Whywouldn't you want to say that you proved your hypothesis correct? What other reasons might there be to explain yourfindings?al« PreviousNext

We would not want to say that we proved our hypothesis correct. Other reasons that might there be to…

Answered: Imagine you predict that it will take a…

Linear Algebra: A Modern Introduction

4th Edition

ISBN:9781285463247

Author:David Poole

Publisher:David Poole

Chapter7: Distance And Approximation

Section7.3: Least Squares Approximation

Problem 31EQ

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In order to determine whether or not a particular medication was effective in curing the common cold, one group of patients was given the medication, while another group received sugar pills. The results of the study are shown below. PatientsCured PatientsNot Cured Received medication 80 10 Received sugar pills 20 50 We are interested in determining whether or not the medication was effective in curing the common cold. The hypothesis is to be tested at the 10% level of significance. The critical value from the table equals a. 2.706 b. 3.841 c. 7.81 d. 5.99
a) If the prevalence rate is 50%, the sensitivity is 85%, and the specificity is 90%, what will the PPV value be? b) What are possible slider values that will produce a PPV value of 1? c) What are possible slider valuse that will produce an NPV value of 1? d) If sensitivity and specificity remain constant while prevalence decreases, what effect does that have on the PPV? e) If prevalence and specificity remain constant while sensitivity increases, what effect does that have on the NPV?
Suppose when you add flexibility to your model by adding higher-order terms or more predictor variables that you begin to see the test or validation error (MSE or SSE evaluated on the test or validation set) begin to increase away from the training error. What kind of a problem are your models experiencing?
A group of educators want to determine how effective tutoring is in raising students' grades in a math class, so they arrange free tutoring for those who want it. Then they compare final exam grades for the group that took advantage of the tutoring and the group that did not. Suppose the group participating in the tutoring tended to receive higher grades on the exam. Does that show that the tutoring worked? If not, explain why not and suggest a confounding variable
Explain why the critical value of t, one-tailed, alpha = .05 is the same as the critical value of t, two-tailed, a .10 .
Answer true or false to each of the following statements and explain your answers. a. In the forward selection method with tenter = 2.00, if the t-statistics for the three predictor variables that have not been entered are 1.72, −1.28, and 0.89, then the forward selection method stops. b. In applying the backward elimination method, a predictor variable is added to the regression equation if the absolute value of its t-statistic is greater than tremove. c. The maximum number of regression equations that need to be determined when selecting a regression equation by backward elimination is equal to the number of predictor variables.
If the value of Cronbach’s alpha is 0.07, it means ___________; a. Research instrument is not reliable b. Research instrument is internally consistent c. Data is reliable d. Data is internally consistent
The following data matrix represents the average exam score for students who study and those who do not at different levels of attendance: Attendance Zero Attendance 50% Attendance 100% Attendance Student Studies 60 75 95 Does not Study 40 40 60 Using the data provided, answer the following: 1) Describe the design (e.g. what are the factors and how many levels of each). 2) What is the DV? 3) State the null hypotheses. 4) State if you ‘expect’ to reject each of the null hypotheses (do not calculate the statistics...just guess based on the data provided). 5) Interpret the meaning of any null hypotheses that you expect to reject. 6) Indicate any post-hoc analyses you would perform.
Answer quickly please. Need answer ASAP. In a winter of an epidemic fu, the parents of 2000 babies were surveyed by researchers at a well-known pharmaceutical company to determine if the company's new medicine was effective after two days. Among 120 babies who had the fu and were given the medicine, 29 were cured within two days. Among 280 babies who had the flu but were not given the medicine, 56 recovered within two days. Is there any significant indication that supports the company's claim of the effectiveness of the medicine? Use α = 0.01
From a statistical perspective, accurate models can be built in data mining with as few as several hundred records. Choose one answer. 1. The statement is contradictory to the idea of data mining sifting through large amounts of data to gain useful information and therefore false. 2. The statement is true because what we need to build a model is 'good' representation of the population, which we can often get with a few hundred records. 3. The statement is false because use of a small number of records would lead to overfitting. 4. The statement is false because several hundred records are very unlikely to lead to an accurate model.
Among a group of high school students, GPA and hours spent on video games are related. The average GPA is 3.0 with SD=0.4.The average hours spent on video games are 6 hours with SD=3.r = -0.2. If a student has a GPA of 3.9, what would we predict for hours spent on video games, using the regression line to make the prediction? Choose the answer that is closest. Group of answer choices 4.5 4 5 5.5
You are testing the null hypothesis that there is no linear relationship between two variables, X and Y. From your sample of n=18,you determine that b1=4.6 and Sb1=1.9. a. What is the value of tSTAT? b. At the α=0.05 level of significance, what are the critical values?

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