Model

Proficiency Rate as a Function of Subject With Bans

Model equations: grades 3–8 all subjects

\[ \text{Louisiana: } \widehat{\text{Proficiency Rate}} = 29.27 + 0.76 \cdot \text{PostBan} \]

\[ \text{South Carolina: } \widehat{\text{Proficiency Rate}} = 39.44 + 3.63 \cdot \text{PostBan} \]

The estimate of the intercept is the predicted score for that row. The other rows estimates show the net difference between that row and the intercept. So, a positive number means it is that much more than the intercept, and a negative means that much less.

Figure 1: Model-predicted proficiency rates before and after cell phone bans for Louisiana (warm colors) and South Carolina (cold colors) across subjects.

Grades 3–8 Models: State Comparison

Red = negative change

Grey = no statistical change

Green = positive change

All subjects

Louisiana: All Subjects (G3-8)
Variable Estimate 95% CI Lower 95% CI Upper
Pre-Ban (Intercept) 29.27 28.24 30.31
Post-Ban Change 0.76 −1.98 3.49
South Carolina: All Subjects (G3-8)
Variable Estimate 95% CI Lower 95% CI Upper
Pre-Ban (Intercept) 39.44 38.15 40.73
Post-Ban Change 3.62 0.74 6.51

ELA

Louisiana: ELA (G3-8)
Variable Estimate 95% CI Lower 95% CI Upper
Pre-Ban (Intercept) 38.08 36.94 39.23
Post-Ban Change 0.57 −2.47 3.60
South Carolina: ELA (G3-8)
Variable Estimate 95% CI Lower 95% CI Upper
Pre-Ban (Intercept) 44.70 43.47 45.94
Post-Ban Change 3.63 0.87 6.38

Math

Louisiana: Math (G3-8)
Variable Estimate 95% CI Lower 95% CI Upper
Pre-Ban (Intercept) 28.48 27.44 29.51
Post-Ban Change 1.65 −1.09 4.39
South Carolina: Math (G3-8)
Variable Estimate 95% CI Lower 95% CI Upper
Pre-Ban (Intercept) 33.89 32.49 35.28
Post-Ban Change 3.62 0.51 6.74

Science

Louisiana: Science (G3-8)
Variable Estimate 95% CI Lower 95% CI Upper
Pre-Ban (Intercept) 24.90 23.92 25.87
Post-Ban Change 0.30 −2.26 2.86

No matching South Carolina district data available for Science.

Social Studies

Louisiana: Social Studies (G3-8)
Variable Estimate 95% CI Lower 95% CI Upper
Pre-Ban (Intercept) 23.56 22.51 24.60
Post-Ban Change 4.12 1.55 6.68

No matching South Carolina district data available for Social Studies.

This is the only statistically significant difference as the confidence interval does not incude 0 change. The other subjects have (within a 95% certainty range) a non-zero chance that the impact is 0.

Grades 3–12 Models (Louisiana)

Grades 3-12: All Subjects
Variable Estimate 95% CI Lower 95% CI Upper
Pre-Ban (Intercept) 29.84 28.79 30.90
Post-Ban Change 0.35 −2.43 3.13
Grades 3-12: ELA
Variable Estimate 95% CI Lower 95% CI Upper
Pre-Ban (Intercept) 38.60 37.46 39.75
Post-Ban Change 0.48 −2.56 3.52
Grades 3-12: Math
Variable Estimate 95% CI Lower 95% CI Upper
Pre-Ban (Intercept) 29.03 27.96 30.11
Post-Ban Change 1.38 −1.44 4.20
Grades 3-12: Science
Variable Estimate 95% CI Lower 95% CI Upper
Pre-Ban (Intercept) 24.34 23.19 25.49
Post-Ban Change 0.58 −1.97 3.12
Grades 3-12: Social Studies
Variable Estimate 95% CI Lower 95% CI Upper
Pre-Ban (Intercept) 23.70 22.73 24.67
Post-Ban Change 2.59 0.06 5.12

This is also the only viable model becuase you can say with 95% certainty that there is a positive effect.

Cell Phone Ban Effects by Grade Group (Louisiana)

Figure 2: Combined boxplot and scatterplot distributions comparing the policy effect of cell phone bans across grade groups in Louisiana (warm palette).

Cell Phone Ban Effects by Grade Level & Subject

Table 1
Louisiana: Ban Effect by Grade Level & Subject
Green = 95% CI Excludes 0 (Statistically Significant) | Grey = 95% CI Includes 0
Subject Grade Level Pre-Ban Intercept (%) Ban Effect (%) Std Error 95% CI Lower 95% CI Upper
All Subjects Grades 3-8 29.27 0.76 1.39 −1.98 3.49
All Subjects Grades 8-12 29.84 0.35 1.41 −2.43 3.13
ELA Grades 3-8 38.08 0.57 1.54 −2.47 3.60
ELA Grades 8-12 38.60 0.48 1.55 −2.56 3.52
Math Grades 3-8 28.48 1.65 1.39 −1.09 4.39
Math Grades 8-12 29.03 1.38 1.43 −1.44 4.20
Science Grades 3-8 24.90 0.30 1.30 −2.26 2.86
Science Grades 8-12 24.34 0.58 1.29 −1.97 3.12
Social Studies Grades 3-8 23.56 4.12 1.30 1.55 6.68
Social Studies Grades 8-12 23.70 2.59 1.29 0.06 5.12
Table 2
South Carolina: Ban Effect by Grade Level & Subject
Green = 95% CI Excludes 0 (Statistically Significant) | Grey = 95% CI Includes 0
Subject Grade Level Pre-Ban Intercept (%) Ban Effect (%) Std Error 95% CI Lower 95% CI Upper
All Subjects Grades 3-8 46.48 3.62 4.60 −11.02 18.27
All Subjects Elementary (G3-5) 50.60 4.60 5.14 −11.76 20.96
All Subjects Middle School (G6-8) 42.35 2.65 4.22 −10.77 16.07
English High School (English II) 74.12 1.68 2.43 −6.06 9.41
Math High School (Algebra I) 56.85 2.15 2.99 −7.36 11.66