Which Equation
A survey finds that out of 75 people, 39 prefer Spotify and 28 prefer Apple music, what percentage of people had an answer that was not Spotify or Apple Music?
What is a one proportion z test
Smoking rate in town in the past was 21%. A sample of 100 people was taken and found that 86 were non-smokers. Is there enough evidence that smoking habits have changed at the 0.1 level?
z=-1.719, p=0.0856, reject the null
You are doing a before and after statistical significance test, what kind of t test are you running?
Matched Pairs design
The formula for the standard error of a t confidence interval
What is s/sqrt(n)?
Suppose a study evaluates the effectiveness of a new drug for treating hypertension. The researchers match participants on their age, gender, BMI, and baseline blood pressure and then randomly assign the members of each pair to receive the drug or a placebo.
What is a matched pairs design
In a representative sample of 1168 American adults, 747 said they were not financially prepared for retirement. Construct a 95% confidence interval to estimate the proportion of all American adults who are not financially prepared for retirement.
[0.612, 0.668]
Your company wants to improve sales. Past sales data indicate that the average sale was $100 per transaction. After training your sales force, recent sales data (taken from a sample of 25 salesmen) indicates an average sale of $130, with a standard deviation of $15. Did the training work? Test your hypothesis at a 5% alpha level.
t=10, cv=1.711, reject the null
The sample size that gives a margin of error of at least 2 inches for a study of the length of rhinoceros horns that has a sample mean of x̄=8in and a sample standard deviation of s=1in with a t* value of 6.12.
What is 10 Rhinos?
A teacher claims that the mean score of students in his class is greater than 82 with a standard deviation of 20. If a sample of 81 students was selected with a mean score of 90 then check if there is enough evidence to support this claim at a 0.05 significance level.
What is a z-test of significance
A concern was raised in Australia that the percentage of deaths of Aboriginal prisoners was higher than the percent of deaths of non-Aboriginal prisoners, which is 0.27%. A sample of six years (1990-1995) of data was collected, and it was found that out of 14,495 Aboriginal prisoners, 51 died ("Indigenous deaths in," 1996). Does the data provide enough evidence to show that the proportion of deaths of Aboriginal prisoners is more than 0.27% at the 0.01 level?
z=1.90, p=0.029, fail to reject
We have the potato yield from 12 different farms. We know that the standard potato yield for the given variety is µ=20. x = [21.5, 24.5, 18.5, 17.2, 14.5, 23.2, 22.1, 20.5, 19.4, 18.1, 24.1, 18.5]. Test if the potato yield from these farms is significantly better than the standard yield at the 0.05 level.
t=0.201, not significant, fail to reject null
A horticulturist is planning a greenhouse experiment with 20 individually potted tomato plants to compare two fertilizer treatments. Ten plants are randomly assigned to fertilizer A, and the remaining are assigned to fertilizer B.
What is a two-sample t test
At the beginning of the Fall 2016 semester a representative sample of World Campus STAT 200 students was surveyed. The students were asked if they were currently dieting to lose weight. In the sample of 524 students, 184 said that they were dieting to lose weight. Construct a 95% confidence interval for the proportion of all World Campus STAT 200 students who are dieting to lose weight.
[0.310, 0.392]
Equation for matched pairs t test
A professor wants to know if her introductory statistics class has a good grasp of basic math. Six students are chosen at random from the class and given a math proficiency test. The professor wants the class to be able to score above 70 on the test. The six students get scores of 62, 92, 75, 68, 83, and 95. Can the professor have 90 percent confidence that the mean score for the class on the test would be above 70?
What is a one-sample t test