The proportion of nurses that view the current state
of EBP favorably would correspond to responses for the agree and strongly
agree ratings. The neutral, disagree, and strongly disagree ratings
can be combined to indicate those nurses that do not rate EBP favorably.
Create a new column, “EBP Favorability” that combines
the agree and strongly agree responses into a “Favorable”
level and the remaining responses combine into the “Not Favorable”
level. This new column can be created using the JMP recoding feature.
Before using the Recode command, you will need to remove the List
Check option from the column containing the responses to this survey
question. For this recoding, we want to create a new column called
“EBP Favorability” by highlighting the column “All
of the practice changes so far have been practical and fit well with
the workflow of the unit” and selecting Cols > Recode and
choosing “New Column” option, as shown in
Figure 2.8 Completed Recode Dialog to Create EBP Favorability Column.
We do not want to overwrite
the original 5-point Likert responses as they may be needed in a future
analysis.
The JMP Distribution platform allows
us to summarize the EBP Favorability column and compute a confidence
interval for the proportion of nurses who view EBP favorably. The
frequency distribution for the EBP Favorability column is shown in
tabular and graphical form in
Figure 2.9 JMP Distribution Output for EBP Favorability. The mosaic
plot was obtained from the red triangle menu.
The histogram shows more detailed information than does
the mosaic plot. The mosaic plot may be a preferable visualization
when there are space limitations or a large number of nominal or ordinal
variables to summarize. Of the nurses that responded to the survey,
33% have a favorable opinion of the current implementation of EBP
changes in their unit.
A confidence interval
for the proportion of nurses who view EBP favorably can be obtained
from the Distribution platform by selecting Confidence Interval from
the red triangle menu associated with the EBP Favorability variable.
A 95% confidence level is chosen for this case.
Figure 2.10 JMP Confidence Interval Output for EBP Favorability shows the
JMP confidence interval output.
The best estimate of
the proportion of nurses that view EBP favorably is 0.33. A 95% confidence
interval for the proportion of respondents who view the EBP implementation
favorably is [0.27, 0.40]. There is 95% confidence that the true
proportion of respondents who view EBP changes at the hospital favorably
lies between 0.27 and 0.40. The 95% confidence level means that on
repeated sampling we would expect 95% of such intervals to contain
the true proportion. Different confidence levels can be chosen, but
95% is commonly used in health care applications. The confidence
interval takes into account the precision with which the sample proportion
was estimated.