PSYC*1010 Chapter 8: Intro to Hypothesis Testing Flashcards
What is a hypothesis test?
A statistical procedure that uses sample data to evaluate a hypothesis about a population
What is the basic assumption about the effect of a treatment?
If the treatment has an effect, a constant amount will be added or subtracted from each score
What is assumed about the shape and standard deviation of a population after treatment?
The shape and standard deviation for the population after treatment is the same as the original population
What is the unknown population?
The population after treatment
What are the four steps of a hypothesis test?
- State the hypothesis and alpha level
- Set the criteria for a decision
- Collect data and compute sample statistics
- Make a decision
How are hypotheses stated in a hypothesis test?
Stated as two opposing hypotheses in terms of population parameters about the unknown population
What does the null hypothesis state?
That there is no change, difference, or relationship for the general population (the IV has no effect on the DV)
What does the alternative hypothesis state?
That there is a change, difference, or relationship for the general population (the IV has an effect on the DV)
T or F: The null hypothesis and alternate hypothesis are mutually exclusive and exhaustive
True
Which hypothesis is used to predict what type of sample should be obtained?
The null hypothesis
What is the notation used to state hypotheses for two-tailed tests?
H0: μ with treatment = μ without treatment
H1: μ with treatment ≠ μ without treatment
What is the alpha level?
The probability value used to define the concept of “very likely” in a hypothesis test
What is the critical region?
The extreme sample values that are very unlikely (as defined by the alpha level)
What is the conclusion of a hypothesis test if sample data fall in the critical region?
The null hypothesis is rejected
What is used to define the exact location for the boundaries that define the critical region?
The alpha level probability and unit normal table
In a hypothesis test, how is the sample data compared to the hypothesis?
By computing a z-score that describes where the sample mean is located relative to the hypothesized population mean from H0
What is the formula for calculating z-score of a sample mean?
z= (M-μ)/σM
Which statistic is used to make a decision about the null hypothesis?
The z-score
What are the two possible outcomes of a hypothesis test?
- The null hypothesis is rejected
- The null hypothesis fails to be rejected
What conclusion is made about the hypothesis if the data are located in the critical region?
The null hypothesis is rejected
What conclusion is made about the hypothesis if the data are not located in the critical region?
The null hypothesis fails to be rejected
What is a test statistic?
A statistic that summarizes the sample data in a hypothesis test and is used to determine if the data is in the critical region (ex. z-score)
How can the z-score be stated as a ratio?
z= the actual difference between the sample (M) and the hypothesis (μ) / the standard difference between M and μ with no treatment
What does a large value for a test statistic indicate?
That the sample data are very unlikely to have occurred by chance alone
What is a type I error?
- Occurs when a null hypothesis is rejected that is actually true
- The conclusion that a treatment did have an effect when it actually had no effect
What is a type II error?
- Occurs when a null hypothesis fails to be rejected but was actually false
- The conclusion that a treatment did not have an effect when it actually did
Which type of error has the most severe consequences?
Type I
What is the probability of a type I error?
The alpha level
Is it possible to determine a single, exact probability for a type II error?
No
How is the probability of a type II error represented?
Represented by the symbol β