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Guess that test statistic!
Interpretation
Paired or Unpaired?
One tailed or two?
Definitions
Perform a hypothesis test!
100
A researcher is planning a psychological intervention study, but before he proceeds he wants to characterize his participants' depression levels. He tests each participant on a particular depression index, where anyone who achieves a score of 4.0 is deemed to have 'normal' levels of depression. Lower scores indicate less depression and higher scores indicate greater depression. He has recruited 25 participants to take part in the study. This test will tell him whether his sample is representative of the normal population (i.e., do they score statistically significantly differently from 4.0).
What is one sample t-test? population SD is unknown, n < 30
100
Given an alpha of 0.05, I would do this to the null hypothesis if my p-value was 0.50.
What is reject the null.
100
Twelve cars were equipped with radial tires and driven over a test course. Then the same 12 cars (with the same drivers) were equipped with regular belted tires and driven over the same course. After each run, the cars’ gas economy (in km/l) was measured. Is there evidence that radial tires produce better fuel economy?
What is paired data and a one-tailed test?
100
This error occurs if we reject the null hypothesis H0 (in favor of the alternative hypothesis HA) when the null hypothesis H0 is true.
What is Type 1 error
100
A Little League baseball coach wants to know if his team is representative of other teams in scoring runs. Nationally, the average number of runs scored by a Little League team in a game is 5.7. He chooses five games at random in which his team scored 5 9, 4, 11, and 8 runs. Is it likely that his team's scores could have come from the national distribution? Test with 95% confidence. What type of test do we run?
One sample t-test sample under 30, pop SD unknown
200
Within a school district, students were randomly assigned to one of two Math teachers - Mrs. Smith and Mrs. Jones. After the assignment, Mrs. Smith had 30 students, and Mrs. Jones had 25 students. At the end of the year, each class took the same standardized test. Mrs. Smith's students had an average test score of 78, with a standard deviation of 10; and Mrs. Jones' students had an average test score of 85, with a standard deviation of 15. This test statistic will test the hypothesis that Mrs. Smith and Mrs. Jones are equally effective teachers.
What is the independent samples t-test.
200
Given this hypothesis- H0: p = .03 HA: p < .03, you determined the test statistic to be z= -2.39. This is the corresponding p-value.
What is 0.0084
200
A farmer decides to try out a new fertilizer on a test plot containing 10 stalks of corn. Before applying the fertilizer, he measures the height of each stalk. Two weeks later, he measures the stalks again, being careful to match each stalk's new height to its previous one. The stalks would have grown an average of 6 inches during that time even without the fertilizer. Did the fertilizer help?
What is paired What is one tailed.
200
The number of values in the final calculation of a statistic that are free to vary.
What is degrees of freedom?
200
A Little League baseball coach wants to know if his team is representative of other teams in scoring runs. Nationally, the average number of runs scored by a Little League team in a game is 5.7. He chooses five games at random in which his team scored 5, 9, 4, 11, and 8 runs. Is it likely that his team's scores could have come from the national distribution? Test with 95% confidence. What are the null and alternative hypothesis in statistical notation AND in written form?
H0: mu = 5.7 HA: mu /=/ 5.7 Null: The team is representative of other teams in scoring runs. Alternative: The team is NOT representative of other teams in scoring runs.
300
A herd of 1,500 steer was fed a special high‐protein grain for a month. A random sample of 29 were weighed and had gained an average of 6.7 pounds. This statistic will test the hypothesis that the average weight gain per steer for the month was more than 5 pounds.
What is a one sample z-test. no pop SD n<30
300
Given this hypothesis- H0: p = .75 HA: p /=/ .75, you determined the test statistic to be z= 1.87. This is the corresponding p-value.
What is 0.0614 Double the tail for 2 tailed tests!
300
A research study was conducted to examine the differences between older and younger adults on perceived life satisfaction. A pilot study was conducted to examine this hypothesis. Ten older adults (over the age of 70) and fifteen younger adults (between 20 and 30) were give a life satisfaction test (known to have high reliability and validity).
What is unpaired data and two tailed test?
300
The probability of making a Type I error.
What is the alpha?
300
A Little League baseball coach wants to know if his team is representative of other teams in scoring runs. Nationally, the average number of runs scored by a Little League team in a game is 5.7. He chooses five games at random in which his team scored 5, 9, 4, 11, and 8 runs. Is it likely that his team's scores could have come from the national distribution? Test with 95% confidence. What are the degrees of freedom AND What is the critical value?
t-crit=2.776
400
The managers of a local record shop want to know which days of the week employees are absent in a five day work week. Most employers would like to believe that employees are absent equally during the week. Suppose a random sample of 60 managers were asked on which day of the week did they have the highest number of employee absences. This test would allow them to determine the which day of the week most employees were absent.
What is the Chi Square Goodness of Fit.
400
What factors can increase power?
What is increase sample size, decrease variation.
400
Cedar-apple rust is a (non-fatal) disease that affects apple trees. Its most obvious symptom is rust-colored spots on apple leaves. Red cedar trees are the immediate source of the fungus that infects the apple trees. If you could remove all red cedar trees within a few miles of the orchard, you should eliminate the problem. In the first year of this experiment the number of affected leaves on 8 apple trees was counted; the following winter all red cedar trees within 100 yards of the orchard were removed and the following year the same apple trees were examined for affected leaves. Is there evidence that removing the red ceder trees decreased the incidence of disease?
What is paired data and one-tailed?
400
A single value used to estimate the population parameter.
What is a point estimate?
400
A Little League baseball coach wants to know if his team is representative of other teams in scoring runs. Nationally, the average number of runs scored by a Little League team in a game is 5.7. He chooses five games at random in which his team scored 5, 9, 4, 11, and 8 runs. Is it likely that his team's scores could have come from the national distribution? Calculate the test statistic
tobs = 1.3195
500
Jackson et al. (2013) wanted to know whether it is better to give the diptheria, tetanus and pertussis (DTaP) vaccine in either the thigh or the arm, so they collected data on severe reactions to this vaccine in children aged 3 to 6 years old. This test would allow him to see if there is a relationship between location of injection and negative reactions.
What is a chi square test of independence.
500
Given that alpha = .05 for a one tailed test, this is what you would do to the null for a test-statistic of z = 1.7.
What is reject the null. (zcrit is 1.65 for one tailed test)
500
Is a sample of adult daughters taller, on average, than their mothers?
Paired data? One-tailed test
500
It indicates the probability of not making a Type II error.
What is power?
500
A Little League baseball coach wants to know if his team is representative of other teams in scoring runs. Nationally, the average number of runs scored by a Little League team in a game is 5.7. He chooses five games at random in which his team scored 5, 9, 4, 11, and 8 runs. Is it likely that his team's scores could have come from the national distribution? Test with 95% confidence. Is the p-value greater than or less than .05? Do you reject or fail to reject the null?
Fail to reject