There's a much better article on this here:

Can we trust casualty figures from the Hamas- run Gaza Health Ministry.

In the past, the US state department’s annual human rights report indirectly relied on the same ministry’s casualty figures in quoting UN statistics drawn from Palestinian data.

Omar Shakir, the Israel and Palestine director at Human Rights Watch, said he saw no evidence that the numbers were being manipulated.

“We have been monitoring human rights abuses in the Gaza Strip for three decades, including several rounds of hostilities. We’ve generally found the data that comes out of the ministry of health to be reliable,” he said.

“When we have done our own independent investigations around particular strikes, and we’ve compared those figures against those from the health ministry, there haven’t been major deviations.

“Their numbers generally are consistent with what we’re seeing on the ground in recent days. There have been hundreds of airstrikes per day in one of the most densely populated areas of the world.

“We’ve looked at satellite imagery. We’ve seen the number of buildings, and the numbers that are coming out are in line with what we would expect with what we’re seeing on the ground. So you put all those things together and we’re quite confident in the overall casualty numbers.”