You make surface observations and proceed to draw erroneous conclusions.

He may reach the erroneous conclusion that you have strength in the suit.

It was child's play to see through your falsified data and erroneous conclusions.

However, again, that could be an erroneous conclusion on his part.

How could he have come to such erroneous conclusions?

They would undoubtedly come to the same erroneous conclusion that you have.

The results of that erroneous conclusion are often dangerous and sometimes fatal.

"You have come to an erroneous conclusion," he said, perfect calm in his voice.

Notice that I'd already broad-jumped my way to an erroneous conclusion.

Such consideration for someone so obviously not of their class led her to an erroneous conclusion.