Wednesday, 27 May 2020, 10:44 PM
Site: Datatree - Data Training Engaging End-users
Course: Introduction to Data Tree (Intro)
Glossary: Glossary of Terms

Heat map

A two-dimensional representation of data in which values are represented by colors. Heat maps communicate relationships between data values that would be would be much more difficult to understand if presented numerically in a spreadsheet.

- CASRAI Dictionary

Hypothesis Test

Testing hypotheses is a common part of statistical inference. To formulate a test, the question of interest is simplified into two competing hypotheses, between which we have a choice. The first is the null hypothesis, denoted by H0, against the alternative hypothesis, denoted by H1 . For example with 50 years of annual rainfall totals a hypothesis test could be whether the mean is different in El Nino and Ordinary years. Then usually • The null hypothesis, H0, is that the two means are equal, i.e. there is no difference. • The alternative hypothesis, H1, is that the two means are unequal, i.e. there is a difference. If the 50 years were considered as being of three types, El Nino, Ordinary, La Nina then usually: • The null hypothesis, H0, is that all three means are equal. • The alternative hypothesis, H1, is that there is a difference somewhere between the means. The hypotheses are often statements about population parameters. In the first example above it might be: • H0, is that µE = µO. • H1, is that µE ≠ µO. The outcome of a hypothesis test is either • Reject H0 in favour of H1, or • Do not reject H0.