STATS 250 Lecture Notes - Lecture 14: Single-Stage-To-Orbit, Dependent And Independent Variables, Scatter Plot
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STATS 250 Full Course Notes
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When making confidence intervals or doing hypothesis testing, it is correct to assume that z is for proportions while t is for means. When given the true mean and standard deviation, you find a z-score. Xbar is a sample mean and is a statistic. Xbar varies each sample and has a distribution. Sample mean is either exactly or approximately normal denoted with n(mu, sigma/square root n) When we know sigma and mu, this is a z-score because we will not be testing a theory; we already know what mu is. So this is when we use z scores even though we"re still talking about the population mean. Regression studies the relationship between two variables that are quantitative and we hope to see some kind of linear pattern so that we can fit a best fitting model called the best square regression line between our two variables. (cid:498)r(cid:499) represents the collation which measures the strength of the relationship.
