The Survey of Study Habits and Attitudes (SSHA) is a psychological test that measures students’ attitudes toward school and study habits. Scores range from 0 to 200. The mean score for U.S. college students is about 115. A teacher suspects that older students have better attitudes toward school. She gives the SSHA to an SRS of 45 of the over 1000 students at her college who are at least 30 years of age. Check the conditions for carrying out a significance test of the teacher’s suspicion.

Short Answer

Expert verified

The simple random sample should be taken and satisfies the following condition:

1. The sample size should be atleast 30.

2. The population size must be greater than the sample size.

3. The sample size should be atleast greater than 10% of the actual population.

Step by step solution

01

Introduction

The distribution of frequencies of all possible results for a statistic of a population parameter refers to the sampling distribution of a given population.

02

Explanation

According to the central limit theorem, whenever the sample size is greater than 30, the sample mean distribution follows a normal distribution. In addition to this, the sample size should be less than 10%of the actual population.

It can be observed that the sample size given is equal to 45, that is, satisfies the normality condition.

Thus, the condition should be applied while choosing a simple random sample and satisfies the following condition:

1. The sample size should be atleast 30.

2. The population size must be greater than the sample size.

3. The sample size should be atleast greater than 10% of the actual population.

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Most popular questions from this chapter

In Chapter 3, we examined data on the body weights and backpack weights of a group of eight randomly selected ninth-grade students at the Webb Schools. Some Minitab output from least-squares regression analysis for these data is shown

1. What conditions must be met for regression inference to be appropriate?

Which of the following is not one of the conditions that must be satisfied in order to perform inference about the slope of a least-squares regression line? (a) For each value of x, the population of y-values is Normally distributed.

(b) The standard deviation σof the population of y-values corresponding to a particular value of x is always the same, regardless of the specific value of x. (c) The sample size—that is, the number of paired observations (x, y)—exceeds 30.

(d) There exists a straight line y=α+βxsuch that, for each value of x, the mean μyof the corresponding population of y-values lies on that straight line.

(e) The data come from a random sample or a randomized experiment.

In a clinical trial 30, patients with a certain blood disease are randomly assigned to two groups. One group is then randomly assigned the currently marketed medicine, and the other group receives the experimental medicine. Each week, patients report to the clinic where blood tests are conducted. The lab technician is unaware of the kind of medicine the patient is taking, and the patient is also unaware of which medicine he or she has been given. This design can be described as

(a) a double-blind, completely randomized experiment, with the currently marketed medicine and the experimental medicine as the two treatments.

(b) a single-blind, completely randomized experiment, with the currently marketed medicine and the experimental medicine as the two treatments.

(c) a double-blind, matched pairs design, with the currently marketed medicine and the experimental medicine forming a pair.

(d) a double-blind, block design that is not a matched pairs design, with the currently marketed medicine and the experimental medicine as the two blocks.

(e) a double-blind, randomized observational study.

In physics class, the intensity of a 100-watt light bulb was measured by a sensor at various distances from the light source. A scatterplot of the data is shown below. Note that a candela (cd) is a unit of luminous intensity in the International System of Unit

Physics textbooks suggest that the relationship between light intensity y and distance x should follow an “inverse square law,” that is, a power-law model of the form y=ax-2. We transformed the distance measurements by squaring them and then taking their reciprocals. Some computer output and a residual plot from a least-squares regression analysis on the transformed data are shown below. Note that the horizontal axis on the residual plot displays predicted light intensity

(a) Did this transformation achieve linearity? Give appropriate evidence to justify your answer.

(b) What would you predict for the intensity of a 100-watt bulb at a distance of 2.1meters? Show your work.

Random assignment is part of a well-designed comparative experiment because

(a) It is more fair to the subjects.

(b) It helps create roughly equivalent groups before treatments are imposed on the subjects.

(c) It allows researchers to generalize the results of their experiment to a larger population.

(d) It helps eliminate any possibility of bias in the experiment.

(e) It prevents the placebo effect from occurring

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