Exam 3 review Flashcards
What is the population distribution?
the distribution of a particular characteristic or variable among all individuals
What is a sampling distribution?
a probability distribution of a statistic (such as the sample mean)
Is the shape of a population distribution always normal?
No
What does the central limit theorem say about the shape of a sampling distribution?
That it will approach a normal distribution as n increases and can be considered normal for n >= 30
What is a confidence interval?
The probability that combining a sample statistic with a margin of error that produces a range of values produces an interval containing the population parameter (95% confident that 0.8435 < P < 0.8720)
what is the t distribution and when is it used?
Similar to normal distribution bit it has thicker tails and changes with sample size n.
used for estimating population parameters for small sample sizes or unknown variances.
what are two ways to make the margin of error smaller?
Increase sample size or lower confidence interval
what is a test of significance?
a test comparing observed data with a claim whose truth is being questioned
what is the p-value?
the probability of obtaining the test statistic or a more significant result under the null hypothesis
What are the four steps in a test of significance?
- Identify parameter and hypotheses
- check if normal
- Find test statistic and p-value and evaluate p-value
- reject or not reject null hypothesis
what is the test statistic?
describes how many standard errors the point estimate falls from the null hypothesis
what is the level of significance, alpha?
the maximum allowed probability of rejecting null hypothesis when it is actually true
when do we reject/not reject the null hypothesis?
When P-value <= alpha, reject
When P-value > alpha, don’t reject
What is a point estimate?
a best guess for the parameter using p hat
When is a hypothesis test right tailed?
H_a: P > P_0
