Chart appears to be plotting the wrong data

[JenniferMurphy]

I have a fairly large data set that I am plotting on a scatter chart. The X values go from 0 to 500. The Y values currently go from 0 to 44. Just two X values have a Y value of 44, 81 and 85. To my eye, these two Y values are not at the same level. The Y value for 85 seems a bit taller than the Y value for 81. What could be causing this?

I'm pretty sure I have the correct data points because if I change both 81 and 85 to 45, the chart above changes those two Y values and then they are even more clearly not at the same level.

I'm happy to post a minisheet, but it's a lot of data and I don't know how to include the chart.

 

[RoryA]

It looks like you're using a smoothed line. You need to turn that off to get 'accurate' plotting (the extra height is not actually at your data point).

 

[JenniferMurphy]

It looks like you're using a smoothed line. You need to turn that off to get 'accurate' plotting (the extra height is not actually at your data point).

That's it. Thanks.