outliers detection using inter quartile range in python

Question

i have a data of 29 rows and four columns namely 'date' , 'volume' , 'area' , 'variations' now i want to find out outliers using IQR methods using python but i am facing following error.

  

Code: 

Q1 = data.quantile(0.25)

Q3 = data.quantile(0.75)

IQR = Q3 - Q1

print(IQR)

lower=(Q1 - 1.5 * IQR)

upper=(Q3 + 1.5 * IQR)

print((data < lower)|(data > upper))

 

Error:

 

TypeError: Could not operate array([nan]) with block values '<' not supported between instances of 'str' and 'float'