December 1, 2020

## Q&A – Calculating average ROI for a group of students

Great question from Pamela:

 Oregon sped regulations for LD referral through RTI specify that ROI needs to be calculated for the RTI group so that the individual ROI can be compared to the RTI group ROI. How do I set up an Excel spreadsheet for that purpose? Do I average CBM scores across students in the group and then compare the group linear regression statistic to the individual linear regression statistic? How do I get Excel to fill in the average for me?

Response:

If you used a spreadsheet similar to the ones on this web site, individual student ROI is calculated for you.  If you highlighted that column, you could enter a formula that will calculate the average of those ROIs to give you a group comparison.  To answer your question directly, yes that is one way you could calculate average group ROI.

## Q&A – Rate of improvement for EasyCBM

Great question from Leasha:

 Please help! Our new state policy manual has listed your website as the place to go for calculating our rate of learning for the upcoming school year. Pretty much every county in the state uses Dibels so it is set up and ready to go for them. However, my county uses EasyCBM for reading. Is it possible for me to just edit the benchmark goals, and then the Excel would calculate it properly for students entered, or would I need to do some special tweaking?

My Response:

Absolutely! You can adjusts the benchmarks to whatever you need them to be and the Excel sheet should automatically adjust the calculations for ROI.  Good luck!

## Q&A – Slope for standard scores

Great question from Lavonne:

 My question is similar to that of Jen on July 18, 2011. I am wondering if Rate of Improvement can be graphed and slope comparisons used with standard scores such as those generated by STAR Reading. We also have standard scores on our statewide assessments and could easily generate Excel graphs to show the difference between our student’s performance and that reuqired to pass. We can easily generate our own Excel graphs, we just want to make sure the data is valid.Thank you. P.S. Thanks so much for this site!

My response:

You can calculate slope for scores that have an equal interval between data points.  STAR Reading, STAR Math, and STAR Early Literacy is a good example of non-CBM data and has been validated as a data set for which you can calculate slope.  Joe Kovaleski and colleagues (2013) just published a book that describes using rate of improvement with computer adaptive tests (CATs), specifically with STAR assessments. I highly recommend getting a copy!

Kovaleski, J. F., VanDerHeyden, A. M., & Shapiro, E. S. (2013). The RTI approach to evaluating learning disabilities. New York, NY; Guilford Press.