Comparative Analysis – How to create a “Best in Class” graph
Overview: This document describes step-by-step how to produce graphs, comparing the
performance of your organisation, with a comparator (region, national, or peer organisations).
Last updated by: Intelligence and Assurance Team, HCAI Improvement Programme
Last updated date: April 2010
CONTENTS:
Why use comparative analysis? ....................................................................................... 2
Downloading the data ....................................................................................................... 2
Creating the data tables.................................................................................................... 2
Creating the graphs ........................................................................................................ 11
To produce a Best in Class matrix .................................................................................. 14
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Why use comparative analysis?
Producing comparative analysis graphs is useful for organisations as it allows them to analyse data
in the two ways outlined below.
Firstly, it provides a tool to let organisations quickly see how they are performing against their peers
so they can see if their rate of infection is better or worse than the other organisations in the
selected group. For example, organisations with fewer admissions should not have more infections
than organisations with more admissions.
Secondly, it allows a best rate of performance within a group to be calculated and displayed so that
organisations can measure how far away they are from best practice within a group,iI.e. the closer
your organisation is to the best rate line the better comparatively they are performing.
The Best in Class Matrix is another way of viewing your data and splits performance of all
organisations into four quadrants. This enables you to not only compare your organisation with
those nationally but also to compare against specific sub-sets of organisations which are similar to
you, whether it be admissions or any other indicator of organisation size/activity (e.g. activity, length
of stay).
Downloading the data
In order to produce the “Best in Class” graphs you will need to download the following data:
• Actual number of cases for the Healthcare Associated Infections you wish to compare
• Admissions data or another indicator of trust size/ activity
Get the actual number of cases for the Healthcare Associated Infection
1. To download this information visit the HPA
website (see screen shot on left)
http://www.hpa.org.uk/
2. Click on the Topics tab (see arrow on screen
shot).
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3. Click on the Infectious Diseases link on the left
of the page (see arrow on screen shot).
4. Scroll down and click on the Healthcare
Associated Infections link.
5. Scroll down and click on the link to the
mandatory surveillance.
To download C. difficilie Acute Data:
1. Click on the C. difficile Infection tables.
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2. Click on the Monthly: Acute Trust and Primary
Care Organisation (PCO) results by month for a
13 month period.
3. Click on the Monthly Trust apportioned counts
of C. difficile in patients aged 2 years and
over (Excel spreadsheet).
4. Save the file to your local network or machine
when prompted.
To download MRSA Data:
5. If you wish to download MRSA data then
navigate Mandatory Surveillance page (step 5)
and click on the MRSA Bacteraemia tables.
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6. Click on the Monthly acute trusts results by
month.
7. Click on the Monthly counts of MRSA
Bacteraemia (Excel spreadsheets).
8. Save the file to your local network or machine
when prompted.
NB: If you cannot locate the information you require, contact the HPA (details can be found on the
HPA website under Contact Details).
Get the admissions data
9. To do this visit the HES website:
http://www.hesonline.org.uk/
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10. Click on Accessing the data, which is found on
the left hand side of the screen.
11. Click on Freely available data.
12. Click on Inpatient data.
13. Click on Inpatient data.
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14. Click on Hospital providers tables.
15. Click on the first link under the Excel format
(XLS) heading to download the most recent data
file.
16. Click on Save to save the file to your local
network or machine when prompted.
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17. The Admissions data is shown in the Admissions column
NB: If you cannot locate the information contact HES, details can be found on their website.
You now have the 2 sets of data to enable you to start building your comparative analysis.
Creating the data tables
For the purposes of this document, the comparative analysis report will be built in a excel
spreadsheet, though you might want to use systems you have locally (i.e. an Access database).
1. Taking the information from the HPA website, insert the trust type, name and code, and
actual cases into an excel table, grouping the data by trust type.
2. If you have data for more than one time period then add these values together to find the
total number of cases for each trust for the data period you have downloaded.
3. Your excel worksheet should look like the sheet below:
4. Insert a column before the Total Cases column. Give this column a heading of Ordinary
Admissions. Using the data downloads from the HES website insert the number of
ordinary admissions for each organisation into this column.
5. Your excel worksheet should now look like the sheet below:
6. Insert a column after the Total Cases column. Give this column a heading of rate per 1000
admissions. Enter the formula below into each row of the new column to calculate the rate
per 1000 admissions:
=Total number of cases for the period divided by number of ordinary admissions multiplied by
1000
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e.g. If your worksheet is set up exactly the same as above then the formula in F2 will be
“=(E2/D2) * 1000”
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7. You now need to calculate the following information for each trust type:
• Maximum number of admissions
• Minimum rate
8. Sort the records by trust type then add a blank row between each trust type so that the data
is grouped by trust type.
9. Calculate the maximum admissions value for each trust type by clicking in the empty row
under the admissions values for each trust type and entering the following formula:
=MAX(range)
e.g. in the example below the formula in D15 would be =MAX(D2:D14)
10. Calculate the minimum rate per 1000 admissions value for each trust type by clicking in the
empty row under the rate per 1000 admissions values for each trust type and entering the
following formula:
=MIN(range)
e.g. in the example below the formula in F15 would be =MIN(F2:F14)
11. On a different worksheet you now need to calculate the start and end points for the best
rate line for each trust type.
12. Enter the following column headings into the worksheet:
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Taking each trust type in turn follow the steps below:
13. Enter the Trust type e.g. Acute Specialist into the Trust Type column.
14. In the Cases per 1000 admissions column enter the minimum rate per 1000 admissions
for the trust type.
15. In the Max admissions column enter the maximum admissions value for the trust type.
16. Calculate the values for the Cases at max admissions column using the formula below:
= Max admissions divided by 1000 multiplied by Cases per 1000 admissions
e.g. in the example above the value in D2 would be = (C2/1000) * B2
17. The Max admissions value is the final horizontal co-ordinate and the Cases at max
admissions is the final vertical co-ordinate for the best rate line for the trust type
18. Insert a row underneath the values you have entered and enter a zero in the Max
admissions and Cases at Max admissions columns.
You will need to use the values created at point 17 and 18 later for creating the best rate line.
19. Repeat this process for all the trust types.
You now have the data to create your best in class graphs.
Creating the Graphs
1. For each trust type from the first table you
created take the following information:
a. Trust code
b. Trust name
c. Ordinary admissions
d. Total cases
2. Using the Excel chart function create a scatter graph with this data, with admissions on the
horizontal axis and cases on the vertical axis
The instructions below assume your worksheet is in the above format.
3. Select all the values in the Ordinary
Admissions and Total Cases
columns for the trust type you are
creating the graph for.
4. Click on the Chart Wizard button.
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5. Select XY (Scatter) as the Chart
Type and make sure the first Chart
sub type is highlighted.
6. Click Next.
7. Click on the Series.
8. Enter a title for your Series into the
Name field.
9. This will create the scatter graph you
now need to create the best rate line.
10. Click on the Add button.
11. Enter “Best Rate” into the Name
field.
12. You will need to use the best rate start and end-points you calculated earlier.
13. Select the two values in Max admissions column for the trust type as the X Values.
14. Select the two values in Cases at Max admissions for the trust type as the Y Values.
15. Click on Next.
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16. Enter a title for your Chart.
17. Enter Admissions in the Value (X)
axis box.
18. Enter Cases in the Value (Y) axis
box.
19. Click on Next.
20. Click on Finish.
21. This should create a graph similar to the one below which can then be formatted to your
requirements.
22. To join the dots of the Best rate, hover over one of the two data points and double click to
open up a dialogue box called Format Data Series. Double click on the tab called Patterns
and then under the area called Line, select Custom and change the format of the line to the
desired colour and weight. Click OK.
23. To highlight your organisation:
• Look up the number of ordinary admissions and HCAI cases from the table.
• Then on the graph hover over the points at the graph where the co-ordinates for your
organisation will be.
•
•
When located, double click on
the point and change the colour
so your organisation is
highlighted.
Click OK.
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To produce a Best in Class Matrix
24. Once you have your graph above, you may wish to go one-step further and split the Trust
data in to one of four squares (quadrants):
¾ High admissions, high infections
¾ High admissions, low infections
¾ Low admissions, high infections
¾ Low admissions, low infections
This will help you to see how your performance differs from a smaller subset of specific Trusts
within your group that are close to your type of Trust, e.g. Acute Specialists. These Trusts can
also be easily identified from the data.
25. The resulting graph will look as below. As you can see, the Trust highlighted as a red
square falls into the quadrant of High admissions, high infections.
Best in class graph
High adm issions, high infections
Low adm issions, high infections
50
45
40
35
Cases
30
25
0
50000
20
100000
15
150000
200000
10
5
Low adm issions, low infections
0
Inpatient Adm issions
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High adm issions, low infections
250000
26. This Trust would then look to improve performance so that it falls into the high admissions,
low infections quadrant below it – as shown below.
27. In a Best in Class matrix, axes cross at the points on the scale which you think should be
applied to split the data into quadrants.
28. For example, you may decide that a high admissions Trust is any Trust with admissions
over 100,000 and a high number of cases may be any above 20 or even above your own
Trust target.
29. To change the position of the axes, double click on the y axis (by clicking on any number
on the axis) and the following screen will appear:
30. In the option which asks for Value (x) axis
place the value at which you would like
the y axis to cross the x axis, e.g. 20 cases. Make sure that this box is not ticked too.
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31. To bold the lines, go to the Patterns tab in the same dialogue box and in the “Weight” pull
down menu – select a slightly thicker line. This should change the thickness of the axes
line.
32. Repeat the same with the x axes, crossing the axes at the value you choose, e.g. 120,000.
Double click on any value on the x axis, change the value at which to cross and again,
make sure this box is not ticked. Change the thickness of the axes line in the same way as
described in the step above.
33. Lastly you may wish to label your quadrants with text boxes such as “high admissions, high
infections” or “low admissions, low infections” (as shown in the above graph in step 24).
To label a quadrant, go to View in your Excel Toolbar and select Toolbars and ensure that
the Drawing Toolbar is ticked.
34. Once you have the drawing Toolbar, the menu button (shown with arrows) will enable you to
create a text box and type your label in there. You may need to then drag the text box to sit
on the graph in the position you need it to be in and resize font and box size.
35. If there are a small number of Trusts in your quadrant you may wish to identify exactly who
those Trusts are from the data, using the instructions in step 22 and 23 above.
36. Viewing the data in this way will enable you to drill down and compare yourselves to specific
Trusts similar to yourselves, enable you to contact other Trusts to share best practice and
monitor your improvements in performance over time as you move in to the right quadrant!
37. Remember, you can plot your infections data against any metric, whether it is Trust
admissions, Activity or Length of stay. Specifically for Infection Control, you can use it to
monitor HCAI performance against hand-hygiene compliance, etc. You can also use it for
internal measures, for example to compare specialties, directorates or wards within your
Trust.
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38. An example of an internal use is below.
High Los, high infections
7
Ward 6
No. of Cdiff cases
6
Ward 9
5
Ward 4
4
Ward 5
Ward 7
3
0
1
2
3
4
5
6
Ward 23
Ward 1
Ward 2
7
8
9
Ward 8
1
0
High LoS, low infections
Ward length of stay
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10
Ward 10