Look at the chart below, for example. I set up an log scale $SPX chart with a secondary $NYA chart from the "indicator" selector. Height scale of the secondary $NYA chart (indicator) was set to 1.0 (scale 1:1). I struck a line on the $SPX portion of the chart, then copied and pasted an exact duplicate of it on the secondary $NYA below (read below to see my little technique to do that).
At first glance, the $NYA is obviously accelerating faster than the $SPX! But look again. Nope, you're WRONG!!! Look at the y-axis price scales and you will see that in Stockcharts, even if you have the log scale setting turned on, the secondary price charts added via "indicator" ARE ARITHMETIC/LINEAR, NOT LOGARITHMIC.
Now you know why I did that slope comparison on two separate primary charts with identical settings. Be very careful when interpreting those indicator price charts in Stockcharts, especially where large y-axis differences in price exist.
Copy and paste of line segments in Stockcharts~
With this chart, I went to "annotations". From there, I clicked on "Detach". "Detach" mode gives you an x-y axis indicator at the screen bottom from where you can identify & record the x & y axis points of the two points of a line segment you strike. I struck my first line segment on the $SPX chart, and then a second duplicate line segment, directly over the top of the first line segment, using the identical x-y points I recorded when I struck the 1st line. If you do it perfectly, it looks like there is still only one line there, but there are now actually two there. I clicked the "selection tool" icon (top-left icon), clicked on the line segments and dragged the copy segment down to wherever I wanted it. Voila, a perfect parallel line.
Of course, you can't directly copy a segment between two different charts. In that case, all you can do is overlay and align a straight edge on your monitor over the first chart, leave it in place on the monitor, go to your second chart, strike a line along your straight edge, then move it into place with "selection tool". Unfortunately, your line segment points can't be verified for exact duplication or perfection, but you can get it very close with a good eye and patience.
If you know of better ways, please let me know.
