Choose the correct test
A researcher predicts that loud music decreases a person’s hearing. On a test of Hearing sensitivity, the population mean for normal volume listeners is 19.5. A sample of 20 people who avidly listened to loud music daily, produces a sample mean = 17.3 with an estimate of the standard error of the sample mean = 5.25.
One sample t test
A researcher at UC Riverside wants to determine is women sleep significantly longer than men.
H0: u1 ≤ u2
H1: u1 > u2
2 samples independent t, N1 = 6, N2 = 5, non-directional 2 tails.
tcrit =±2.262
The comparison of students who studied with those who did not study and the outcome of their final exam score. What is the DV?
Final exam score
The p-value reported is .051. What decision do you make?
Retain H0
Ten brand new, identical Volkswagen cars were obtained for a gasoline usage comparison. Five of the cars were driven using regular unleaded gasoline. The other five cars were driven using super unleaded gasoline. Which statistical test should be used?
Independent t test
A teacher wants to know how well the AVID students in her class perform compared to all students. The population mean is 50 with standard deviation of 6. Her class of 31 students has an average score of 55.
H0: u = 50
H1: u ≠ 50
1 sample t, 2 tails, N = 61, alpha = 0.05
tcrit = ± 2.000
Researchers compare performance scores of students who eat breakfast in the morning and students who don’t eat breakfast in the morning. What is the IV?
Eat breakfast. or Type of eating breakfast condition
The reported sig. is .04999133. What decision do you make?
Reject H0
A team of UCLA engineers wanted to know if a new campus library had any positive effect on exam scores. A sample of 57 sociology students who studied in the library earned an average of 89 on their exam. Did the new building affect average exam scores? The average UCLA exam score for all majors is 85 and variance of 15.
1 sample z test.
A student wonders if instructors consume more or less cannabis than students at a local college we will not disclose. She asks 15 instructors and 14 students to record the number of joints each smoked during a 4 of July Holiday weekend.
H0: u1 = u2
H1: u1 ≠ u2
N total = 25, 2 groups, alpha = 0.01, directional less than
tcrit = -2.500
What is the measurement scale for: Grade Point Average GPA?
The squared point biserial correlation coefficient reported is .412. What is the interpretation?
This is a large effect size.
Average glucose levels for Americans with prediabetes is 126mg/dl. A group of 25 individuals participated in an aerobic fitness program to lower their blood glucose levels. After seven months the group was evaluated to identify if the program had significantly lowered their blood glucose levels. The mean blood glucose for the group was 120mg/dl with a variance of 6.5. Was the program effective in lowering blood glucose?
1 sample t test.
An army researcher was interested in the long-term efficacy of pre-workout supplements. He took two random groups of 8 soldiers each from the same company. One group took pre-workout prior to the test while the other group took a placebo. He administered a physical test to each participant ('0' score being the worst, '300' score being perfect) and scores were recorded.
H0: u1 = u2
H1: u1 ≠ u2
t, group 1 N = 23, group 2 N = 25, negative direction, S21 = 1.23 and S22 = 1.65
tcrit = -1.684
What is the measurement scale for: Change in number of mood swings?
Interval
Mean difference is -23; estimated standard error of the difference between the sample means is 2.334; in step 2 we reported 1-tail critical t of 1.729 for 19 degrees of freedom. State the critical t for the confidence interval.
2.093
A research study was conducted to compare men’s and women’s satisfaction with their workplace. A survey was given to 10 men and 10 women. The scores were recorded from 1-10 with high scores showing high satisfaction and low scores showing low satisfaction.
Independent t test
A team of Standford neuropsychologists wants to test a new medication to see if it decreases depression. The scientists measured decrease in depression by the number of tasks the patients performed. The more tasks performed means that depression goes down. In the population of Southern California, the average level of depression is 73. A sample of 10 participants who have taken the medication has a mean of 75 with a standard deviation of 20.
H0: u ≤ 73
H1: u > 73
1 tail, population mean = 50 and standard deviation of population = 2, on the left side of the distribution
zcrit = -1.65
What is the measurement scale for: Type of genre you read?
Nominal
If the variance of the population is 4, sample size is 25, what is the standard error of the mean for a 1 sample z test?
Standard error of the mean = 0.4