Chapter 9 Pt 2 Flashcards
What is a single sample?
subset of individuals from larger population
What is a single sample used to compare?
Statistics (mean/proportion) to known population parameter
What is the null hypothesis?
Sample statistic does no differ from the hypothesized or known population parameter or differs in a way not predicted by alternative
What is the alternative hypothesis?
Outcome being predicted or tested by the research study
What is a z-score?
Indicates a raw score’s distance from the mean in standard deviation units
What is a one sample t-test?
Determine whether a sample of observations could have been generated by a process with a specific mean
What is a t-distribution?
Symmetric/bell-shaped, heavier tails, Shape changes with the sample size, family of distributions
When is a one sample t-test used?
When population variance is unknown and sample size is small (n<30)
What happens in a t-test as the sample size increases?
As the sample size increases the t-distribution approaches the standard normal distribution
What is the difference between the cut off points in z-scores vs t-scores?
With t values are not constant but vary depending on the degrees of freedom
What does the t-table give?
Critical values of t
A researcher is interested in whether the reaction time to a signal change of 24 student drivers is slower than the RT published in news report?
T-test, right-tailed
A clinical psychologist wants to compare the scores of his therapy group of 18 clients on a measure of self-confidence to the results in a published paper that includes the mean and standard deviation.
Z-test, two-tailed
Social worker intends to survey a sample of 20 households in a neighborhood in a predominantly low-income area to see is household income is above or below the poverty level.
T-test, two-tailed
What is a degree of freedom?
Number of observations that are completely free to vary
