week 5 fundamentals Flashcards
What is a census?
A census collects data from the entire population of interest
It can be expensive, time-consuming, and impractical.
What is statistical inference?
Statistical inference uses sample data to make inferences and answer research questions, estimating values of corresponding population characteristics.
What is point estimation?
Calculating sample mean, sample standard deviation, and sample proportion is called point estimation.
Define a simple sample.
A simple sample of size n from a finite population of size N is selected such that each possible sample size of n has the same probability of being selected.
What is a sample mean?
The average of the sample values.
What is a sample standard deviation?
A measure of the amount of variation or dispersion in a set of sample values.
What is a sample proportion?
The ratio of the number of observations of a certain value to the total number of observations in the sample.
What is the relationship between point estimates and population parameters?
Point estimates will always differ somewhat from values of corresponding population parameters.
What is a sampling distribution?
The distribution of a statistic (like the sample mean) obtained by selecting all possible samples of a specific size from a population.
What properties does a sampling distribution have?
It has an expected value (mean), standard deviation of the mean (standard error), and a characteristic shape or form.
What does the Central Limit Theorem state?
When the population has a normal distribution, the sampling distribution of the sample mean is normally distributed for any sample size.
When can the sampling distribution be approximated by a normal distribution?
As the sample size becomes large (typically n > 30).
What is interval estimation?
Interval estimation is used to generate an estimate of the value of a population parameter by adding or subtracting a margin of error to the point estimate.
What is the T distribution?
A distribution used when the sample size is small or when the population standard deviation is unknown, characterized by degrees of freedom.
What are the types of errors in hypothesis testing?
Type 1 error (rejecting a true null hypothesis) and Type 2 error (failing to reject a false null hypothesis).
What is a null hypothesis?
The expected scenario or behavior of the population that is being tested.
What is an alternative hypothesis?
A proposed alternative explanation to the null hypothesis.
What forms can hypothesis testing take?
- One-tailed test (inequalities in null hypothesis) 2. Two-tailed test (equality in null hypothesis).
What is a significant test in hypothesis testing?
Applications of hypothesis testing that control only for Type 1 errors.
What happens to the T distribution as the degrees of freedom increase?
It narrows, its peak becomes higher, and it becomes more similar to the standard normal distribution.
