Stats 2 Exam 1

Where does the mean fall in a skewed distribution?

mean is pulled towards the tail of the skew

What is the formula for a confidence interval for a population mean?

statistic ± t * (s/sqrt(n))

degrees of freedom for one mean

n-1

What is type 1 error?

reject the null, when the null is actually true

What is type 2 error?

fail to reject the null when the null is actually false

degrees of freedom for two independent means

(n1+n2)-2 is the two sizes are the same, otherwise the smallest n-1

test statisitic for two indepedent means

(mean1-mean2) / estimate of standard error

degrees of freedom for matched pairs

n-1, where n is the number of pairs

What are the degrees of freedom for one-way ANOVA?

df1 = k -1 and df = N - k, where k is the number of samples/treatments and N is the total number of sample sizes

What is the number of pairs in a population for one-way ANOVA?

k(k-1) / 2

What are the degrees of freedom for two-way ANOVA?

df1 = (a-1)(b-1) and df2 = ab(r-1) where a and b are the number of levels of factor A and B and r is the number of replications of each treatment

what are the degrees of freedom for the Kruskal-Wallis test

df = k -1

When to reject the null on a wilcoxon signed rank test

when the test statistic < critical value, because p < 0.05