In a statewide study relating graphing calculator use patterns to achievement, researchers found that:
Students demonstrated higher levels of math performance when a graphing calculator was used.
There was a positive correlation between the residual gain scores and students using a classroom set of graphing calculators.

Dimock, V. and T. Sherron (2006). Final Report of A Study of the Impact of Graphing Calculator Use on State Assessments. Austin, TX, Southwest Educational Development Laboratory: 123.

This study examined the use of graphing calculators over a one year time frame with students
enrolled in Algebra I courses. Researchers sought to answer questions regarding the
relationships among the use of graphing calculators on standardized assessments and student
achievement, levels of access, and classroom use of graphing calculators. The researchers
recruited participation in the study by high schools in two states. Students took two tests
without using a graphing calculator then took a third test using a graphing calculator.
Researchers examined data with a Repeated Measures General Linear Model (GLM),
Multiple Regression, and Hierarchical Linear Modeling (HLM) to investigate differences and
relationships between mathematics achievement, graphing calculators, and student and
teacher variables. Researchers found that students demonstrated higher levels of math
performance when a graphing calculator was used. There was a positive correlation between
the residual gain scores and students using a classroom set of graphing calculators. Using
HLM, researchers constructed a model where 12% of math achievement variability was
statistically explained by: (1) student use of a graphing calculator; (2) student ownership of a
graphing calculator; (3) student access and use of a classroom set of graphing calculator; (4)
student familiarity in graphing more that one function; (5) teacher familiarity in writing a
program using the graphing calculator; and (6) connecting graphing calculators to motion
detectors, computers, or other graphing calculators.