# T-test

## Single-sample t-test & Confidence Interval – Excel & StatCrunch

When we do not know the population standard deviation sigma, σ, and the sample size, n, is less than 30, we use the t-test to evaluate a claim. Consider the following problem: A scientist thinks the mean waste recycled by adults in the US is now more than one pound per person per day. In …

## Recognizing problem types: Hypothesis tests

Read the problem looking for keywords and values: What type of variable is the focus of the problem? Is it quantitative, e.g. a mean, or categorical, e.g. a proportion or percent? How many variables are of concern? Is(are) the population(s) standard deviation, sigma, given? Are sample variances equal or are you instructed to assume they …

## Setting up Hypothesis Tests

The Null and Alternative The most common problem I noticed on this assignment was caused by failing to properly identify the appropriate null and alternative hypotheses. In part, this is due to the Evans text’s somewhat confusing explanation of how to do this – the “burden of proof” approach. There is a much simpler approach …