Lecture 7 Flashcards
measures of location
mean, median, quartile
measures of spread
range (max-min), interquartile range, variance, standard deviation
define hypothesis
A statistical hypothesis is a statement of belief about population parameters.
null hypothesis
• The null hypothesis, symbolized by H0, is a statement claiming that there is no difference between the assumed or hypothesized value and the population
parameter; null means “no difference.”
alternative hypothesis
• The alternative hypothesis, which we symbolize by H1 (some textbooks use HA) is a statement that disagrees with the null hypothesis.
two tailed test?
A two-tailed test is a statistical test in which the critical area of a distribution is two-sided and tests whether a sample is greater than or less than a certain range of values. If the sample being tested falls into either of the critical areas, the alternative hypothesis is accepted instead of the null hypothesis.
one tailed test?
A one-tailed test is a statistical test in which the critical area of a distribution is one-sided so that it is either greater than or less than a certain value, but not both. If the sample being tested falls into the one-sided critical area, the alternative hypothesis will be accepted instead of the null hypothesis
p-value?
A p-value is the probability of getting the outcome observed (or one more extreme), assuming null hypothesis to be true
type 1 error?
We denote the probability of making type I error as α. Significance level. Typically in biology/medicine equals 0.05 (except omics and pharmacy).
type 2 error?
• We denote the probability of making type II error as β. The test correctly rejects the null hypothesis with probability 1 − β, the latter we define as the power of the test. Typically between 0.8 and 0.95.
If p < 0.05, then we
reject null hypothesis
If p ≥α, we..
accept null hypothesis
how we form conclusion, when we reject null hypothesis?
difference is statistically significantly different
how we form conclusion, when we accept null hypothesis?
There is no evidence to reject H0, because … no statistically significant difference…
which is the strongest normality test?
Shapiro-Wilk
what is the objective of t test?
to compare the means of the population
what we should do before applying t-test?
test for normality
when we reject null hypothesis?
when p-value is smaller than 0.05
when can we use ANOVA?
to compare the mean differences between any number of groups or treatments
what is anova test?
An ANOVA test is a way to find out if survey or experiment results are significant. In other words, they help you to figure out if you need to reject the null hypothesis or accept the alternate hypothesis. Basically, you’re testing groups to see if there’s a difference between them
what is dependent variable?
Y (variable whose averages are compared) is metric, normally distributed.
factor variable
categorical. Due to it we know the group to which the respondent belongs.
when we use one way anova?
used when you want to test two groups to see if there’s a difference between them
when we use two way anova?
used when you have one group and you’re double-testing that same group. For example, you’re testing one set of individuals before and after they take a medication to see if it works or not.
