Thanks! I mostly intend for this app to be a teaching aide, i.e. soemthing I pull up while lecturing and walk them through what's going on.

• Regression estimate: The estimated slope of the line, or (to interpret it causally), the estimated effect that X has on Y
• Standard deviation: How spread apart the values are from the mean. For example, rolling a six-sided dice has smaller variance than rolling a 20-sided dice. The 20-sided dice gives values that are more spread out. In other words, higher SD = more noise.

You can tell how much noise there is by how sparead out the blue dots are around the line, yes.