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Results

Results are the outcome of a seriation (ordering). The object of archaeological seriation is to determine an ordering, or seriation, of a number of objects (artifacts or assemblages) that replicates as closely as possible their historical order of creation. To do this, OptiPath relies on the assumption that the artifacts share characteristics or features whose measure evolves gradually (or unimodally) over time. The ordering of artifacts that produces the most gradual (or most unimodal) evolution of all features for all artifacts is considered the optimal seriation. The results of a seriation are presented in the Artifacts table or Assemblages table (depending upon whether or not you are using assemblages) and the Results table.

Results Menu

Show/Hide Table allows you to open/close the results table and view the seriation results (and create, delete and edit the artifacts or assemblages).

Show/Hide Data is a toggle that specifies whether artifact/assemblage feature data are to be displayed in the results table. This item toggles between Show Data and Hide Data. This menu item is disabled if the artifacts table is not open.

Seriate initiates the calculation of a new seriation. There is a corresponding Seriate button on the toolbar.

Reverse reverses the order of the current seriation. Seriation is an ordering technique, not a dating technique. Shortest Path seriation is able to assign relative dates to the items being seriated; however, this depends upon the dates you enter as the Earliest and Latest dates for the seriation. Even then, without Earliest and Latest dates for each item, OptiPath is not able to orient the direction of the relative dating - i.e. it does not know which end is earliest and which is latest. The Reverse command allows you to reverse the order of the current seriation, as seen in the Results table. There is a corresponding Reverse button on the toolbar.

Gradual Index will display the overall Gradual Index for the current seriation. Modifying the data or changing the feature parameters can affect the values of this statistic. This menu item is disabled if the Results table is not open.

Unimodal Index will display the overall Unimodal Index for the current seriation. Modifying the data or changing the feature parameters can affect the values of this statistic. This menu item is disabled if the Results table is not open.

Show/Hide Errors allows you to open/close the errors dialog where OptiPath computes and reports the order and date errors for the current seriation. To compute Order Errors, OptiPath compares the Index of an item, with the Order computed by OptiPath. To compute Date Errors, OptiPath compares computed date of an item with the user entered Earliest and/or Latest date for the item. The Raw numbers reported are the average values of the absolute values of the differences between the computed numbers and the correct numbers. The Normalized numbers are the same values expressed as percentages. The normalized order error is expressed as a percentage of the total number of items (artifacts or assemblages) in the seriation. The normalized date error is expressed as a percentage of the overall allowed date range of the seriation, as determined by the Earliest and Latest dates for the seriation. If the Index numbers or Earliest or Latest dates for the items being seriated are not known, the errors analysis is meaningless. A random seriation would be expected to have normalized errors of about 33.3%. The Errors report allows users to test the effectiveness of OptiPath by seriating a set of items whose order and dates are known. See Errors for more information.

Export allows you to export the results to a tab delimited text file. See Export to Text File.

Help will bring up this documentation.

Results Table

The Results table contains information for each artifact (assemblage) not excluded. All entries in the Results table are read only and cannot be modified in this table although they can be modified in the Artifacts (Assemblages) table.

Right clicking on the table will bring up a pop up menu of available actions.

Index is an integer value assigned to an artifact (assemblage) that allows you to sort artifacts (assemblages) in a table.

Artifact/Assemblage is a name that uniquely identifies the artifact or assemblage. Artifact and assemblage names are restricted to 50 characters. The artifact or assemblage name is required for each artifact.  An artifact or assemblage cannot have the same name as any other artifact or assemblage and cannot be the same as an OptiPath reserved name: Earlier, Later, Unimodal Index..

Earliest is a value representing the earliest possible date that can be assigned to this artifact. The Earliest date should not be less than the overall Earliest date for the seriation set in the Seriations window. If you use an Earliest date other than Earliest date for the overall seriation, OptiPath will use a different algorithm to solve the seriation and computation times will be noticeably longer - see Optimal Path Seriation.

Latest is a value representing the latest possible date that can be assigned to this artifact. The Latest date should not be greater than the overall Latest date for the seriation set in the Seriations window. If you use a Latest date other than Latest date for the overall seriation, OptiPath will use a different algorithm to solve the seriation and computation times will be noticeably longer - see Optimal Path Seriation.

Order indicates an artifact's sequential (ordinal) position in a seriation. This field can only be modified by the user in the Artifacts (Assemblages) table. However, you can reverse the order of the seriation by choosing Reverse from the Seriate menu or by clicking the Reverse button on the toolbar.

Date indicates an artifact's date as estimated by OptiPath in performing a seriation. This field cannot be modified by the user.

Distance is the distance of the artifact (in "feature space") from the virtual EARLIER artifact in the path determined by the seriation. The Distance indicates an artifact's precise relative position in a seriation. The virtual EARLIER artifact will have an order (or sequence) number of 0 and a Distance of 0. The first real artifact will have an Order number of 1 and a Distance greater than or equal to 0 reflecting its relative distance (in "feature space") from the EARLIER artifact. The next artifact will have an Order number of 3 and a Distance greater than or equal to the distance of the preceding artifact and reflecting its distance (in "feature space") from the EARLIER artifact; and so on. The total distance of the path (the Distance of the virtual LATER artifact) is normalized to 1. This field cannot be modified by the user.

Rate indicates an artifact's rate of change from the previous artifact in the seration as computed by OptiPath. The rate of change is the difference in distances divided by the difference in dates. This field cannot be modified by the user. This information can also be seen in the Results table.

Features - there is a separate column for each feature. Feature names cannot be edited in this table. Each cell in a feature column reflects the value of the measure for that feature for artifact in the corresponding row. Values are computed by OptiPath from the input data. Computed values can be seen in the Values table. Values can be numbers or letters or words, depending upon the feature data type. You can enter and edit your data in the Data table or in the Artifacts (Assemblages) table.

Unimodal Index is a measure of the unimodality of a seriation or an ordered sequence of numbers. The unimodal index is scaled from -1 to 1. If each feature's data values were plotted against their assigned dates, a graph showing a single peak would be perfectly unimodal and have a Unimodal Index of 1. A graph with a single valley would be perfectly anti-unimodal and would have a Unimodal Index of -1. A random ordering of the data would have an expected Unimodal Index of 0. The overall Unimodal Index for the seriation is the weighted average (using the Weights in the Features table) of the individual feature indices.

Gradual Index is a measure of the gradualness of a seriation or an ordered sequence of numbers. The gradual index is scaled from -1 to 1, -1 the value for a 'perfectly nonunimodal' sequence (one valley), and 0 the expected value for a random seriation. A seriation with a Gradual Index of 1 cannot be made more gradual by reordering. A seriation with a Gradual Index of -1 could not be less gradual. The overall Gradual Index for the seriation is the weighted average (using the Weights in the Features table) of the individual feature indices.