Overview of Comparative Analysis

Comparative analyses allow you to select multiple indicators in order to compare their readings over time. Analyses typically compare readings from similar indicators that can be numeric, calculated, cumulative, descriptive, or performance indicators. For example, a technician might want to compare pressure readings for a group of pumps over a six-month period. You can view the results in charts as well as tables, forms, and dashboards.
When creating a comparative analysis, you can choose between four analysis types: basic, advanced, degradation, and none.
Note: If you select None as the analysis type, the Analysis view does not display the Analysis tab and graph. Readings for the time period, current values, and activities are shown in tables.
This topic explains the types of indicators that can be included in an analysis, how time periods are set up, and the features of the analysis types: basic, advanced, and degradation. Its topics are:

Types of Indicators to Compare

To be displayed in a graph, indicator readings can be expressed as numeric data or states. You can include numeric, cumulative, and descriptive type indicators in an analysis. Examples of numeric indicators include those that measure temperature, pressure, or resistance. Examples of cumulative indicators are odometers, counters, and so on. Examples of descriptive indicators are condition of belts, corrosion, and oil level.
In the case of numeric and cumulative indicators, a reading consists of a number and a unit of measure. Because calculated and performance indicators provide a numeric result, they can also be included in an analysis.
Readings for a descriptive indicator are expressed in terms of states rather than numeric values. For example, the value of a reading for an indicator that measures the condition of a valve might say that it is in good condition or worn out. The graphs for these indicators include the indicator states on the secondary axis (Y or vertical).
Note: To include descriptive indicators, select the advanced analysis type.
Tip: You can view a list of the analyses in which an indicator is included. Open the Indicator window and select the Usage view, Comparative Analyses tab.
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Time Periods Used in Analyses

Time periods can be defined as either a fixed period or a moving period. When a fixed period is used, the analysis has permanent start and end dates. Analyses of this type are meant to provide a graphical snapshot of the readings during a specific period in the past.
In contrast, when a moving period is used, the start and end dates of the period advance as time goes on. For example, you might want to have an analysis that shows the readings for the flow and pressure of a pump for the last two weeks. In this case, the beginning and end of the period are relative to the current date. This type of analysis is more suitable for inquiry-type graphs when you are interested in seeing current information.
You can define the duration of a moving period using one of the following options:
If you use “In the last…”, you must also enter a duration (for example, in the last six months).
A fixed period has the same options, plus “Custom” and “On or after”. Select “Custom” to define the start and end dates. Select “On or after” to set the start date.
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Summary of Features by Analysis Type

The following chart lists the features and their options and indicates the analysis types that make them available. The sections that follow describe the features in detail.
Axis title1
Yes2
Yes3

1
Not shown in degradation analyses.

2
In degradation analyses, activities are shown in the Analysis view, Asset Activities tab only.

3
For degradation analyses, customization of the readings chart appearance is needed to show secondary axes.

Basic Analysis Type

Create a basic comparative analysis to quickly view readings for as many indicators as you like. The following features are available in the basic analysis type. This section explains:

Readings Over Time

If you are using the default options for the basic analysis type, the Analysis view, Analysis tab shows a graph of the indicator readings collected over the time period that you selected. The legend at the bottom of the graph shows each indicator’s name, asset, color, and shape for reading occurrences. Here is an excerpt from a basic analysis:
In the Analysis view, Indicators tab, you will also find the Readings tab. This tab lists the readings by indicator and includes each indicator’s asset, value collected, and collection date and time.
Readings that triggered alarms are shown in the colors assigned to their alarm states. For example:
You can double-click a reading to open its Indicator Reading window, view full details, acknowledge alarms, and so on.
In the analysis properties, the Show gauge sidebar option is selected by default. This allows you to select a reading in the table on the Readings tab to quickly view the value collected and alarm status in the gauge. For example:

Current Values

In analysis properties, the Show current values option is selected by default. This provides the Indicators tab, Current tab in the Analysis view. The Current tab lists the indicators included in the analysis, their assets, current values, and last collection date.
You can select the Form icon () to view the information for individual indicators.
Select the Chart icon () to view the values in the default bar chart. Here is an excerpt:
You can double-click an indicator to open the Indicator to Compare dialog to view information about the indicator and current reading.
You can also change the chart type for current values. See Chart Options.

Asset Activities

You can display one asset’s activities in the Analysis and Asset Activities tabs in the Analysis view. Select from these activities:
In the graph, the Activities legend shows the shapes and colors that represent each activity. This excerpt shows the activities and the legend:
In the Analysis view, select the Asset Activities tab to view tables of the asset’s activities. You can choose from these table configurations:

Chart Options

You can adjust the appearance of charts:
Select a different chart type for reading history, shown in the Analysis view, Analysis tab. This option is available for basic analyses only
Select a different chart type for current values, shown in the Analysis view, Indicators tab, Current tab when you select the Chart icon
Turn Show gauge sidebar on or off
For readings and current values chart types, you can override the default style of graphs. There are many styles to choose from, for example:
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Advanced Analysis Type

The advanced analysis type includes all of the features of the basic type. In addition, you can select a subset of indicators to include in charts, show asset health indexes, and set up secondary axes. This section explains:

Chart Indicators

As with basic analyses, use the Indicators to Compare tab to browse for as many indicators as you like. Then, on the Chart Indicators tab, select up to 12 indicators from this list to compare in the readings graph, shown in the Analysis view, Advanced Analysis tab.
Your indicators-to-compare list must include any indicators that you wish to display on secondary axes.

Secondary Numeric Axis

In an advanced analysis, you can add a secondary axis for numeric indicators and set the text for the axis title. You can assign as many as 12 indicators to the secondary axis.
A secondary numeric axis is useful when indicators use different units of measure, for example, indicators that measure flow and pressure. They are also handy in analyses with many numeric indicators and readings that vary over a wide range of values. The second axis can make readings easier to see. For example, consider an analysis with 12 indicators that show a wide range of values collected. Here is an excerpt:
You could add a secondary axis and assign the indicators with the lowest values to it. For example:
The “Low readings” axis shows the collected values on a scale that makes the indicator lines more legible.
When you hover the mouse pointer over a reading, you will see that the collected value is from the secondary axis. In this example, the value is 2.000 psi:

Secondary Descriptive Axis

In an advanced analysis, you can add a secondary axis to show the indicator states for a descriptive indicator. You can set the text for the axis title, and you can add up to 12 descriptive indicators to the analysis.
Alternatively, you can add one descriptive indicator to an analysis that otherwise compares only numeric indicators. The Analysis view, Advanced Analysis tab displays the indicator states on a secondary axis, as well as the indicator readings. This example shows numeric and descriptive secondary axes:

Side-by-Side Comparison

In an advanced analysis, you can select Show side-by-side comparison in the Properties view, Options tab. This adds the Dashboard tab to the Analysis view. The dashboard displays as many as 12 indicators. Here is an excerpt from an example analysis:

Asset Health Indexes

In an advanced analysis, you can show as many as 12 asset health indexes. Indexes can be shown alone or in conjunction with indicator readings.
In the Analysis view, the Health Indexes tab shows Readings and (if selected in properties) Current Values tabs. For example, the Current Values tab shows the indexes as forms. Use the arrow keys to move from one index to the next.
If indicators have also been selected, the Advanced Analysis tab displays both readings and health indexes.

Degradation Analysis Type

Use the degradation analysis type to compare readings from as many as 12 degradation indicators.
Tip: Comparative analyses can also be created from a failure mode in a risk-based inspection analysis. In the Maintenance Action Plan window, select the Degradation Rates view and the Comparative Analyses tab and click New. This feature is not available for failure modes created for the damage mechanisms library.
In the Analysis view, the Degradation Analysis tab, Comparison tab displays a graph of readings that occurred during the designated time period, as well as the degradation reading values, next inspection dates, and end-of-life dates. For example:
The black horizontal line in the graph represents a degradation rate based on the FFP minimum value for the designated indicator. The area below the graph summarizes degradation information for each of the indicators.
The Readings, Degradation Rates, Remaining Allowance, and Degradation Dashboard tabs present side-by-side views of degradation information. The Degradation Dashboards tab presents each indicator on its own tab. For example: