Name the test or C.I.
A researcher is interested in testing the itching side effect some people reported when using a new brand of hairspray. The researcher asks a group of women to use the new hairspray, and then records how often each woman scratches her head in an hour.
1 sample t-test
The three conditions for a 2-sample confidence interval are the same as the conditions for a 2-sample t-test of significance. TRUE/FALSE
TRUE
The symbol used in Ho and Ha for a hypothesis test for a one-sample mean is _____. An example is shown below.
Ho: ___ = 0.85
Ha: ___ < 0.85
For a two sample t-test with two lists of data provided (L1 andL2), you will calculate a t value for data list 1 and another t value for data list 2. TRUE/FALSE
FALSE
A researcher found a statistically significant difference (p-value = 0.0008) between the heights of 30 year old adults that eat one piece of fruit or more per day (vs. those who do not eat fruit). The difference is 0.10 inches. Though there is statistical significance, there is no __________ significance.
practical
(or real life)
The number of babies born per family in France(F) and Switzerland(S) was compared for a sample of 300 families each. xF = 1.85 sF = 1.3 xS = 1.65 sS = 1.2
2 sample t-test
A sample of 9 students are randomly selected from club X (N=120) and 9 students are randomly selected from club Y (N=80). Is the 10% rule condition met for the two-sample t-test? YES/NO and explain why.
NO, 9 students is not <10% of club Y's members.
What is another way of writing Ho for a two sample t-test besides the format shown below?
Ho: uA = uB
Ho: uA - uB = 0
x1=30 s1=2.1 n1=14
x2=25 s2=1.9 n2=15
What is the value of the standard error of the difference between sample means (two decimal places)?
0.75
What type of test (or interval) is implied below regarding the survival status of the passengers on the Titanic ship that in 1912?
1st class passengers: died, survived, survived, ...
crew: died, died, survived, ...
Question: Estimate the difference in those who survived, 1st class vs crew
Estimate the range for the population mean number of pets a typical U.S. household owns from the list: 0, 4, 2, 0, 1, 1, 1, 5, 0, 2, 0, 0, 3
1 sample t-interval
For sample sizes greater than or equal to _______, we can assume the sampling distribution is normally distributed according to the ______________ theorem.
30, central limit
The hypotheses below imply a __________ hypothesis test.
Ho: uDIFF = 0
Ho: uDIFF > 0
A matched pair test
A t-test results in a p-value of 0.042, for what alpha levels would you conclude "reject the null hypothesis"? Use typical values of alpha = 0.10, 0.05 and 0.01
Reject at alpha = 0.10 AND alpha = 0.05
What is the critical value for a 99% confidence interval for a one sample mean with a sample size of 20?
___ = ____
t* = 2.86
A researcher would like to examine how the chemical tryptophan, contained in foods such as turkey, can affect mental alertness. A sample of n = 9 college students is obtained. The data collected is: L1 video game performance before a turkey dinner and L2 is the video game performance after a turkey dinner. Each student has a before and after score. The average score dropped by 14 points after the meal.
Matched pair t-test
Small sample sizes of n=12 and n=18 were used in a two-sample t-test. Under what conditions could you still proceed with hypothesis test.
If the graphs of both sample data sets are "roughly symmetric" with no strong skew and no outliers.
For a two sample t-test the calculation for t is t = [(xA - xB) - (uA-uB)] / [sqrt(sA^2/nA + sB^2/nB)]
The value of uA-uB is _____ because _____
0, for Ho it is assumed uA = uB implying the difference in values would be zero
Consider a one-tailed hypothesis for the difference of two means. n1 = 10 and n2=5
Use the t-table or tcdf function to determine the p-value for a where t = 1.5 (use a the "conservative" degrees of freedom)
For d.f. = 4
t-table answer: 0.10<p-value<0.15
tcdf answer: p-value = 0.104
Ho: A river has healthy levels of oxygen for fish
Ha: A river has unhealthy levels of oxygen for fish
A type __ error is worse because ___
II, you will assume the river is healthy but it is actually not safe....it may not get the environmental remediation it needs to improve
Which process is used when the standard error in the calculations is sDIFF / sqrt(n) where DIFF is the difference in the values in L1 and L2.
Matched pair t-test
In an experiment 40 volunteers (not randomly selected) were recruited for a test and half were randomly assigned to treatment A and the other half to treatment B. Has the the random condition been met? YES/NO explain
YES, as long as there has been random assignment of the treatments in an experiment, the condition has been met.
The general formula for the test statistic, t, is the same regardless of whether it is a 1-sample or 2-sample test. What is the formula? (use words, not symbols)
t = (statistic - parameter) / (estimated standard deviation)
A two sample t-test with alpha = 0.10 is hypothesized to be
Ho: uX equals uY Ha: uX does not equal uY
A ____ % confidence interval using the same sample data would need to contain ___ if we can conclude "fail to reject" for the hypothesis test.
90, 0
Ho: u1=u2 Ha: u1>u2
If a hypothesis test for a 2-sample mean has a test statistic, t, equal to 1.45 and associated p-value of 0.06 it means that there is a ____% chance of observing a t value as extreme as 1.45 assuming that ___________________
6%, the null hypothesis is true.