Distance 6.0

Distance 6.0 is the latest version of Distance, and incorporates several new features, as listed below.

New Analysis Capabilities

·       Interface with the free statistics software R (note - R is not included within the download file - it must be downloaded and installed separately for the new analysis engine (below) to function. R is not required for any other part of the program to function.)

·     New analysis engine: Mark-recapture distance sampling (MRDS). Allows analysis of dual observer distance sampling surveys, where probability of detection on the trackline can be estimated. Currently restricted to line transects. 

Other Improvements

·        Better bootstrapping in the CDS and MCDS engine: progress is given on the main toolbar; bootstrap point estimates are given in the output and analysis browser columns (useful for model averaging – see Model averaging in CDS Analysis).

·        Better documentation (e.g., MCDS engine command reference in an appendix) and many more sample projects.

New Analysis Capabilities

·      Better goodness-of-fit testing – q-q plots, K-S tests and Cramer-von Mises statistics for exact data in both CDS and MCDS engines

·      When calculating adjustment terms, you can now scale distance by either truncation distance w or estimated scale parameter σ. 

·      When combining stratum estimates to form a global density estimate, if you weight by effort you can now treat the effort strata as either fixed or random effects.

Graphical User Interface

·    GIS has improved capabilities for coping with projections: the list of candidate projections is much longer and you can now specify projection parameters.

Survey Design

·        Ability to enter study area details into built-in GIS

·        Can then examine properties of user-specified designs, from a wide range of different design classes (e.g., random points, grid of points, line segments, zig-zag lines, etc)

·        Can generate survey plans for the different designs.

New Analysis Capabilities

·        New MCDS engine allows multiple covariates in the detection function

·        Data selection function of the Data Filter now much more powerful.

·        For surveys with nested sample layers (e.g., clusters of points along a line), the user can choose which level to treat as the independent sample for determining encounter rate variance.

·        Analysis engines now calculate AICc, as well as other model selection measures

Graphical User Interface

·        Built-in GIS, based on MapObjects by ESRI (compatible with ArcView)

·        Data Explorer and Analysis Browser consolidated into the Project Browser.  New tabs for Designs, Surveys and Maps added.

·        New Analysis Components window makes it easier to keep track of Data Filter and Model Definitions.

·        Lots of small refinements, e.g. Data Filter and Model Definition properties remember which tab they were last on, making setting up analyses quicker; naming objects is now easier – double click on the names in the Project Browser, or in the Details windows to edit them.

Data Storage

·        Much more flexible data structure – data can be linked from external databases in a variety of formats (although there is no user interface for this yet – has to be done by direct editing of the database).

·        Internal data now stored in DistData.mdb file within separate data folder.  The data folder is also used by default to store the GIS information (ESRI shapefiles).  Distance 4 project is therefore a project file (.dst file) and the associated project folder.

·        More layer types, including coverage probability, nested strata and effort layers, etc.  Can now have unlimited number of data layers in the project

·        New survey object multiple surveys to be stored together in the same project file, but analyzed separately.  Surveys can have different survey methods and different units.

New Utilities

·        Data import now more flexible – can import one or more data layers, and can use ID or Label fields to link to the parent layer.  Various limitations in previous version caused by MS database engine not correctly recognizing the data types of text fields has been worked around.

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