Dear Experts (especially graphing experts),
We have used Stata v. 17 to estimate a mixed piecewise linear growth model. The (very large) dataset is in long format, with between 1 to 6 annual observations of test scores per student, from 2017-2022. Spline variables for time were created the old fashioned way with 2 knots at 2020 (pre-covid) and 2021 (post-covid), to produce 3 growth slopes. The regression command used was:
mixed testscore precov covid postcov || sid:
The estimates all make sense; however, we are struggling to figure out how to graph the predicted slopes. All we want is a simple line graph showing the different slopes for each of the 3 splines from 2017-2022. There are some relevant posts on graphing splines on the help board, but they only seem to be useful if one has used mkspline. Any suggestions?
Thank you in advance!
Rachel
We have used Stata v. 17 to estimate a mixed piecewise linear growth model. The (very large) dataset is in long format, with between 1 to 6 annual observations of test scores per student, from 2017-2022. Spline variables for time were created the old fashioned way with 2 knots at 2020 (pre-covid) and 2021 (post-covid), to produce 3 growth slopes. The regression command used was:
mixed testscore precov covid postcov || sid:
The estimates all make sense; however, we are struggling to figure out how to graph the predicted slopes. All we want is a simple line graph showing the different slopes for each of the 3 splines from 2017-2022. There are some relevant posts on graphing splines on the help board, but they only seem to be useful if one has used mkspline. Any suggestions?
Thank you in advance!
Rachel
