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Basic Statistics for Infection Preventionists
Module 1 – Descriptive Statistics
1. Hand hygiene compliance is tracked as a percent for each nursing unit in your facility. Reading
through a summary of the hand hygiene data for all the units in your facility you find the
following table:
Table 1: Hand Hygiene Compliance by Year
Year
2013
2014
Compliance (%)
Mean
Median
65
67
82
67
Which of the following is the most likely explanation of what happened in 2014?
a. Hand hygiene compliance increased considerably in one or two units that were already
above the median.
b. Some units got much better about hand hygiene but an equal number got much worse.
c. Hand hygiene compliance didn’t change much.
2. Given the data in the table from Question 1, what conclusion can you reach about the change
from 2013 to 2014?
a. The change in the mean is statistically significant.
b. The change in the mean is not statistically significant given that the median didn’t
change.
c. The mean increased in 2014 but we can’t tell if that is a statistically significant change
based only on the available data.
3. A co-worker asks for your help with understanding a report comparing CLABSI rates at all 60
hospitals in your state. According to the report, the CLABSI rate for your facility is at the 80th
percentile. How should you explain this statement?
a. 80% of the patients at your facility get CLABSIs.
b. 80% of hospitals in the state have CLABSI rates lower than your facility’s CLABSI rate.
c. 80 hospitals in the state have CLABSI rates lower than your facility’s CLABSI rate.
d. Out of the 100 CLABSIs identified in your state, your facility has had 80.
4. Which of the following are useful ways of describing the distribution of categorical data?
a. Mean and median
b. Range and standard deviation
c. Positive and negative skew
d. None of the above
Bonus Project
We will not specifically be going over answers to this one in class but you are invited to tackle it as a
personal exercise. That said, you are welcome to bring it up during the Q&A session of the class if you
wish.
Identify a variable you track or collect as part of your job. Determine how you could collect the data
related to that variable so that you would end up with a Nominal variable, an Ordinal variable, and a
Quantitative variable (either Ratio or Interval).
Example:
 Variable = Central Line Presence
 Nominal = Is a central line present? (Yes/No)
 Ordinal = How long has a central line been present? (<2 days, 2-5 days, 6-10 days, 10+ days)
 Ratio = How long has a central line been present? (Exact # of days)