Sublime

Companies can now base important decisions on real, scientifically valid experiments. In the past, any foray into randomized testing (the random assignment to groups that we mentioned above) meant employing or engaging a PhD in statistics or a “design of experiments” expert.

The t-distribution is like the normal distribution (also called the z-distribution) except that it takes the sample size into account.

Let’s assume that you want a 95 percent confidence in your answer. This corresponds to a Z-score of 2, meaning that the number must fall within two standard deviations of the observed mean.

five-step process: Define the question and figure out methodology; collect data; clean and summarize the data using descriptive statistics; process the data and apply hypotheses; make inferences and apply findings.[xii]

your sample mean is unlikely to equal the population mean. The difference between the sample statistic and the population value is the sampling error.

The two parameters in the formula are alpha (1 minus the level of confidence (1 − 0.95 = 0.05)) and the degrees of freedom (sample size minus 1 for a one-sample t), for which t = 2.14.

Bayes' Theorem looks at how likely something is to happen, given that something else has already happened.