Q:

Academic way of saying "On the other hand"

I have two paragraphs in my paper, the previous paragraph ends with 

This shows that TF-IDF is still an important feature for text analysis
  task

and my next paragraph starts with 

On the other hand, various studies suggested that LDA may not work on
  short documents due to insufficient context

Is there another way of begin my next paragraph instead of saying On the other hand but keep the meaning of contrasting? 

A:

"Conversely, various studies suggested that LDA may not work on short documents due to insufficient context." 

A:

There's nothing wrong with On the other hand in any context. 

A:

You could write

"By contrast, various studies suggested that LDA may not work on short documents due to insufficient context." 

Both conversely, "with a reversed relationship", and on the contrary are ok if you are writing about parallel cases; by contrast (or in contrast) suggests a difference but not necessarily a paralled or directly opposite relation.