Statistical Tests

Question 1

what is the purpose of the Chi-squared test & what must the data be?

Answer 1

to test the significance of the difference b/w observed & expected results

data must be categoric & be frequencies

Question 2

what is H0 for Chi-squared test?

Answer 2

that there is no statistically significant difference b/w observed & expected outcomes/frequencies

Question 3

describe the method for a Chi-squared test

Answer 3

degrees of freedom = number of categories - 1

if the X^2 value is less than the critical value, there is no significant difference b/w observed & expected outcomes
any differences are due to chance
so accept H0

if the X^2 value is great than the critical value, there is a significant difference b/w observed & expected outcomes
so reject H0

Question 4

what does P value of 0.05 mean?

Answer 4

the probability that the difference b/w observed & expected outcomes is due to chance is 5%

Question 5

define chance

Question 6

define probability

Answer 6

the likelihood an event will occur

Question 7

what is the purpose of the student’s t-test?

Answer 7

to test the significance of the difference b/w the means of sets of data
takes into account SDs

Question 8

describe the method for a student’s t-test

Answer 8

use formula to get value
if this value is > critical value at P value of 0.05 or less, reject H0

Question 9

why is SD better measure of spread than range?

Answer 9

less influenced by outliers & anomalies

Question 10

what is purpose of a correlation coefficient?

Answer 10

Spearman’s rank correlation coefficient
to test the degree to which the 2 data sets are correlated

Question 11

describe the method for correlation coefficient

Answer 11

-1 perfect -ve correlation
0 no correlation
1 perfect +ve correlation

use formula to get value
if this value is > critical value at P value of 0.05 or less, reject H0