[mlb_hn]

I don't get the justification for labeling the initial block as organic growth, unless they're claiming that only the horizontal stratification is signs of bot activity. The vertical stratification should also be signs of bot activity, and as they point out, many of the supposed bots were in the vertical stratification groups.

For those not familiar with the graphs, the graph shows date followed on x and date created on y. Where there's horizontal stratification, NYT noticed it means the follower accounts that all began following the account at the same time were also created around the same time, indicating a strain of bots. However, when there's vertical stratification, there's a shift in the rate at which accounts are following the account. When the vertical stratification is followed by horizontal stratification, it's an indication that both sets are bots - for example, one scenario is that instead of providing a mix of bots created at different time, someone got lazy and just grabbed a list of bots all created at the same time. However, vertical stratification could also just indicate that the person did something good or bad to change the rate of acquiring new followers so it isn't clear cut. That being said, I'm not sure that justifies labeling the initial section which lacks horizontal stratification as organic.