Stats III Flashcards
What is a sampling distribution?
Distribution of means of samples
What does it mean for a statistic to be an unbiased estimate of a parameter?
equal to population parameter
The is the type I (alpha) error?
Accept Ha, reject H0 when H0 is true
What is the type II error?
Accept H0 when Ha is true
What is the difference between a statistic and parameter?
Parameter = info about whole population
Statistic = info from a sample of a population
The standard deviation of the sampling distribution = ?
SD of sampled pop / n^.5
What is the standard error of the mean?
Standard deviation of sample of means
Standard normal distribution is centered around what? What is the SD?
0
with SD = 1
What is a Z score?
Difference between sample mean and population mean, divided by standard error
When n is sufficiently large, what are the values of mew(xbar) and sigma(xbar)?
mew(xbar) = mew Sigma(xbar) = sigma/n^.5
What is the equation for calculating a confidence interval?
x(bar) + z(sigma) : z = z score, sigma = SD of sample means
90% confident Z score is what?
1.645
95% confidence Z score is what?
1.96
99% confidence Z score = ?
2.58
What is the equation of the margin of error?
Z(sample SD) = SE
What is a statistical hypothesis?
Statement about the numerical value of a population parameter
What is the difference between testing one vs two tails?
one tail means mew does not equal some value
Two tail means that mew is greater than or less than some value
How many samples are used in observational studies?
1
How many samples are used in clinical trials?
2+
What is a test statistic?
Sample statistic computed from information provided in a sample
What is the rejection region?
Area beneath a bell curve where the null hypothesis is true
How do you know to reject or accept the null hypothesis?
if p value >= alpha, then do not reject null
What is the p value?
The probability of observing a value of the test statistic that is at least as contradictory to the null
