(iv) Statistical Analysis
HCUP-NIS sampling design and analysis have been described in previous
HCUP publications10,11. We used the standard published
algorithm and applied sampling weights to generate nationwide estimates.
Results mentioned in this paper are weighted nationwide estimates. Data
was presented as mean (standard deviation) or frequency (percentage) as
appropriate. Continuous data was compared with the two-tailed
independent sample t-test while categorical data was compared with the
Rao-Scott adjustment for chi square test. All results are two-tailed and
at the 95% confidence level. P-value of less than 0.05 was considered
statistically significant for the analysis. All the analysis was
performed using SAS software, version 9.4 (SAS Institute, Cary, NC).
HCUP methods series recommendations were followed for estimates for
standard errors and confidence intervals8.