Scatterplot with regression line: confidence interval or standard error?

[Enrique Prada]

Hi, I have a doubt regarding the option "standard error" of the regression line in scatterplots. I have tried to find if this issue appeared in previous posts of this forum, but I haven't found a clarification about this (apologies if I missed it).

My doubt is whether the "standard error" option generates a confidence interval around the regression line, or if it generates a standard error band (i.e., a band with +-1 standard error around the regression line). On the one hand, I expected that this option would generate a confidence interval, because as far as I know, it is more common to provide a confidence interval. On the other hand, however, the button to include this option says "standard error", and the documentation of the R function that jamovi uses to create scatterplots (scatr::scat) also alludes to standard errors.

This is the R code that jamovi uses to produce a scatterplot with a regression line and a band around the regression line, with some data that I had (I obtained this code using the syntax mode of jamovi - the version of jamovi that I use is 2.3.28.0):

scatr::scat(
data = data,
x = GDP per capita,
y = Women MPs,
line = "linear",
se = TRUE)

In the documentation of scat {scatr} they say: "se: TRUE or FALSE (default), show the standard error for the regression line"

However, as I thought that providing confidence intervals would be more natural, I wanted to double check this. In order to do that, I generated 2 scatterplots in R with ggplot. One had a regression line with a confidence interval (95%) and the other had a regression line with a standard error band. Then I compared them with the scatterplot generated by jamovi, and it looked like the jamovi scatterplot coincided with the scatterplot with a confidence interval! So now I think that perhaps there's a mistake in the documentation and what jamovi produces are confidence intervals instead of standard errors. Could somebody please check this and let me know? If you want, I can provide the R code that I used, and screenshots of the graphs that I generated (although I don't know how to upload images to the forum post).

Thank you in advance. Best,
Enrique

[jonathon]

hi,

so taking a quick look at the source code, we do the following:

ggplot2::geom_smooth(
method = self$options$lineMethod,
se = self$options$lineSE,
formula = y ~ x,
color = theme$color[1],
fill = theme$fill[2]
)

https://github.com/jamovi/jmvplots/blob ... .R#L67-L85

the key argument seems to be `se`, which any normal person would interpret as "standard error". however the documentation says

"Display confidence band around smooth?"

which rather tends to suggest `se` plots a confidence interval, rather than a standard error. let me escalate this.

jonathon