EXAMPLE 8.8 Small Companies versus Large Companies
CASE 8.3 First, we find the estimate of the difference:
Next, we calculate the standard error:
For 95% confidence, we use , so the margin of error is
The large-sample 95% confidence interval is
With 95% confidence, we can say that the difference in the proportions is between 0.18 and 0.47. Alternatively, we can report that the percent usage of audio/ visual sharing through social media by smaller companies is about 32% higher than the percent for large companies, with a 95% margin of error of 15%.