|
State Color |
Red |
Blue |
|
Sample Size |
24 |
26 |
|
Average Crime (per 100,000) |
369 |
327 |
|
Sample Standard Deviation |
120 |
136 |
We are interested in looking at the difference in crime rates for states that were red...
1. When do we use an independent groups t-test? a. b. c. d. When we are comparing means from one sample that has been measured twice. When we are comparing means from two different samples. When we are comparing a sample mean to a population mean. When we are comparing two population means. 2. Which of the following is true regarding the use of t-tests for true experiments versus quasi-experimental designs? a. b. We use the same t-test whether it...
A group of researchers was interested in looking at the change of heart rate when participants engage in a step-up exercise. Step-up exercise is where a person starts with both feet on the ground and then steps up onto a step. In this study, the step is either 5.75 inches off the ground or 11.5 inches off the ground. Subjects were randomly assigned to a step-up exercise on either a 5.75-inch step or an 11.5-inch step. The change in heart...
In Data 4.1 on page 258, we examine a study in which mice were randomly assigned to either a normal light/dark cycle or to have a light on around the clock. According to the paper describing that study, "The global increase in the prevalence of obesity and metabolic disorders coincides with the increase of exposure to light at night." The study is examining whether light at night plays a causal role in the obesity epidemic. In Data 4.1, we examine...
Researchers were interested in comparing the long-term psychological effects of being on a high-carbohydrate, low-fat (LF) diet versus a high-fat, low-carbohydrate (LC) diet. A total of 106 overweight and obese participants were randomly assigned to one of these two energy-restricted diets. At 52 weeks, 32 LC dieters and 33 LF dieters remained. Mood was assessed using a total mood disturbance score (TMDS), where a lower score is associated with a less negative mood. A summary of these results follows: Group...
The consumption of caffeine to benefit alertness is a common activity practiced by 90% of adults in North America. Often caffeine is used in order to replace the need for sleep. One recent study! compares students' ability to recall memorized information after either the consumption of caffeine or a brief sleep. A random sample of 35 adults (between the ages of 18-39) were randomly divided into three groups and verbally given a list of 24 words to memorize. During a...
in comparing the engagement levels of first-year statistics students. In a previous nation-wide study, engagement levels were found to be normally distributed, with µ=60.00, σ=10.00. The lecturer collects a convenience sample of 50 first-year students and finds that her students have a mean engagement level equal to 75.54. What statistical procedure should be used, to test whether there is a significant mean difference in engagement levels between the lecturer’s first year students and the population average? a. One sample Z-test....
Why do we naturally tend to trust some strangers more than others? One group of researchers decided to study the relationship between eye color and trustworthiness. In their experiment the researchers took photographs of 80 students (20 males with brown eyes, 20 males with blue eyes, 20 females with brown eyes, and 20 females with blue eyes), each seated in front of a white background looking directly at the camera with a neutral expression. These photos were cropped so the...
Coaching companies claim that their courses can raise the SAT scores of high school students. Of course, students who retake the SAT without paying for coachinggenerally raise their scores. A random sample of students who took the SAT twice found 427 who were coached and 2733 who were uncoached. Starting with their verbalscores on the first and second tries, we have these summary statistics:Try 1 Try 2 Gainx s x s x sCoached 500 92 529 97 29 59Uncoached 506...
Why do we naturally tend to trust some strangers more than others? One group of researchers decided to study the relationship between eye color and trustworthiness. In their experiment the researchers took photographs of 80 students(20 males with brown eyes, 20 males with blue eyes, 20 females with brown eyes, and 20 females with blue eyes), each seated in front of a white background looking directly at the camera with a neutral expression. These photos were cropped so the eyes...