1. In a study of intra-observer variability in the assessment of cervical smears, 3325 slides were screened for the presence or absence of abnormal squamous cells. Each slide was screened by a particular observer and then rescreened six months later by the same observer, The results of this study are shown below.
Second Observation
First Observation Present Absent Total
Present 1763 489 2252
Absent 403 670 1073
Total 2166 1159 3325
a. Do these data support the null hypothesis that there is no association between time of screening and diagnosis?
The data could also be displayed in the following manner:
Abnormal cells Present Absent Total
First 2252 2166 4418
Second 1073 1159 2232
Total 3325 3325 6650
b. Is there anything wrong with this presentation? How would you analyze these data?