Exam 2 Review Flashcards
- If a certain number of examinations are selected at random and their mean is calculated, what is the expected average score?
Avg is = to given mean
- How to find standard deviation of the average score?
- How to know if the distribution of scores/data is approximately or exactly normal?
Approximately: Around the mean
Exactly: Equal to the mean
What are parameters?
Describe the population
What are statistics?
Describes the sample
What is a subset of a population?
Describes the same group of individuals
What is point estimate?
The sample mean is called a point estimate of the population mean μ.
What is the confidence level?
indicates the probability, with which the estimation of the location of a statistical parameter (e.g. an arithmetic mean) in a sample survey is also true for the population.
What is the margin of error?
a statistic expressing the amount of random sampling error in a survey’s results. The larger the margin of error, the less confidence one should have that the data’s reported results are close to the ‘true’ figures
What is an interval estimate?
estimated range of values for a statistic
What are the following confidence intervals?
90%
95%
98%
99%
90% -> 1.645
95% -> 1.96
98% -> 2.33
99% ->2.57
What’s the critical z-value for a 99% confidence interval?
2.575 or 2.58
- Decreasing the sample size, while holding the confidence level the same, will do what to the length of your confidence interval?
Makes it bigger
- Decreasing the confidence level, while holding the sample size the same, will do what to the length of your confidence interval?
Makes it smaller
You take a random sample from some population and form a 96% confidence interval for the population mean, μ. Which quantity is guaranteed to be in the interval you form?
- x-bar (sample mean)
When asked for the sample standard deviation of the sample mean, what equation should you use?
When asked for the sample standard deviation of the sample mean, what equation should you use?
What is the equation for finding the confidence interval?
Note that for Z just use memorized confidence intervals.
How to find the margin of error of a confidence interval?
(sample standev times confidence interval)
How to find a specific n value given pieces of standev of sample mean formula?
E: Margin of error
Z: Confidence interval value
How to find the standard error of the sample mean of a certain given n value.
How to find the probability of something with normal distribution given mean and standev?
Z = (value-mean) / standev
