Parametric Tests Flashcards
what data can parametric tests test
continuous and discontinuous distributions
examples of continuous data
length, time, mass
what do parametric tests tell you
the probability of a value falling within a range
what is a normal distribution defined by
mean + varience
what is the variance
the standard deviation (from the mean)
what are meristic characters and examples
Countable structures that can’t come in halves eg bristles on a fly, chicks in next
when can you use parametric stats on meristic data
if their distribution is normal
What is the test for normality
Shapiro-Wilk test for normality
what is the null hyp in S-W
normality is the n0
What should you do when testing for normality if two data sets are being compared
both should be tested separately for normality
you do a shapiro-wilk test for normality and you get a significant result, what does this mean
you reject the null hypothesis - your data is NOT normal
what is the population distribution and what are paramiters
pop distribution is defined by parameters - you want to infer something about a population and you describe a population with parameters
what is the standard error of the mean
tells you how different the sample mean is from the population mean =
standard deviation/ square root of the sample no.
what is the central limit theorem
95% of observations will fall in the range of +- 1.96 standard deviations from the mean
why do smaller sample sizes need a bigger value than 1.96
to include 95% of the distribution
