PLEASE HELP! I HAVE POSTED THIS A FEW TIMES AND KEEP GETTING INCORRECT ANSWERS!
ID: 199726 • Letter: P
Question
PLEASE HELP! I HAVE POSTED THIS A FEW TIMES AND KEEP GETTING INCORRECT ANSWERS! I really appreciate the help!
If it is too blurry:
26 12
14 18
14. Two neurologists, Drs. J and K, independently examined 70 magnetic resonance images (MRIs) for evidence of brain tumors. As shown in the table below, the neurologists read each MRI as either "positive" or "negative" for brain tumors. of brain tumors. Dr. K Dr. J Positive Negative Positive Negative 12 18 26 Based on the above information, the overall percent agreement between the two doctors including all observations is (3 points): What is the kappa statistic associated with this dataset? (2 points)Explanation / Answer
1. Observed agreement between the two doctors:
Observe agreement= Number of time both say positive + Number of time both say negative/Total number of observation= 26+ 18/ (26+12+14+18)= 62.9%
2. Proportion of units that are in agreement p= 26+18/70= 0.629
Dr K
Dr J
Total Percentage
Positive
Negative
Positive
26
12
38
Negative
14
18
32
Total Percentage
40
30
70
Proportion of units expected to agree by chance pe= [(38*40)/70 + (32*30)/70]/70
pe= 21.7+13.7/70= 35.4/70= 0.51
kappa coefficient (k)= p-pe/1-pe= 0.629-0.51/1-0.51= 0.119/0.49= 0.243
As the value of 0.243 is between 0.21-0.4 (kappa values), there is a fair agreement between the doctors.
Dr K
Dr J
Total Percentage
Positive
Negative
Positive
26
12
38
Negative
14
18
32
Total Percentage
40
30
70
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