lecture 5 - analysis of qualitative data

Question 1

for evaluating qualitative frequency data (nominal or ordinal data) for ‘goodness of fit’ (with a hypothesized underlying distribution) or for ‘association’ between multiple measures

Answer 1

analysis of qualitative data

Question 2

goodness of fit: we determine the significance of the difference between observed and expected results using _______ statistic
this statistic has positive values only

Answer 2

chi-square

Question 3

for a chi-square with a degree of freedom LESS THAN 1, what is recommended

Answer 3

Yate’s correction (- 1/2 in chi-square formula)

Question 4

true/false: if the df is >1, Yates correction is not required

Answer 4

true

Question 5

true/false: random sampling is not essential for calculation of chi-square

Answer 5

true - but may impact the interpretation (bias) therefore ideally they would be random

Question 6

true/false: observations must be independent for chi-square

Answer 6

true

Question 7

true/false: categories must be mutually exclusive for chi-square

Answer 7

true

Question 8

this is an assumption for chi-square; in all the cells their must be at least 1, with no more than 20% of cells with an expected frequency < 5 for the resulting theoretical distribution to be reasonably accurate

Answer 8

expected frequencies

Question 9

the distribution of chi-square depends on the number of treatments being compared and the number of outcomes. this dependancy is quantified in a degrees of freedom parameter v equal to:

Answer 9

number of rows in the table -1 times the number of columns in the table - 1
v=(r-1)(c-1)