Tik-76.115 Individual Project: Guinea Pig
$Id: gpTestAnalysis.html,v 1.2 1996/04/20 16:13:39 hynde Exp $

Module gpTestAnalysis for result analysis and filtering

The python module gpTestAnalysis defines a new class derived from gpTest and functions for reading, analyzing and filtering the result files. The gpTestLogic module uses following modules:

Load the gpTestAnalysis module this way: 

   import gpTestAnalysis
or 
   from gpTestAnalysis import *

Module gpTestAnalysis defines the gpTestAnalysis class some functions for digging information out of the test items.

1 · Class gpTestAnalysis - for analyzing test results

The gpTestAnalysis class is derived from the gpTest class. Many of the gpTest's methods are not needed so they are redefined as dummy functions to prevent their use accidentally.

A new test object is created, as always in python, by calling the gpTestAnalysis class as a function: 

    test = gpTestAnalysis()

1.1 · Instance variables

The gpTestAnalysis class defines no new instance variables. However, note the meaning of these variables:
test.test_items (list of test items)
List of test items, one for each item ID. During analysis, one test item contains all the answers (by all subjects being analyzed at the same time) to that item in the item's result list.

test.Subjects (list of test subjects)
A list of test subjects whose result files are analyzed at the same time. Usually contains many subjects in contrast to only one when test is being performed for some subject.

1.2 · Methods

test.load_items([filename], [subjects])
Load the test items from the result files of subjects. If subjects is not given, uses the test's subjects list.

Load_items() loads all subjects' result files and merges results from multiple test items with the same ID into one test item. The item's result dictionary then holds all answers for that test item given by all subjects.

After loading the items are in the test object's test_items list.

1.3 · Using the test analysis class

The usage is pretty similar to the using of the gpTest class. First create a new instance of the gpTestAnalysis class: 
   from gpTestAnalysis import *

   # ...

   test = gpTestAnalysis()
Then load the configuration information: 
   test.load_config()
(Assumed that config information is found in the current directory). Then add all the test subjects to the test: 
   for gpid in gpIDs:
      subject = gpTestSubject(test, gpid)
      subject.read_info()
where gpIDs is a list of subject IDs (giving the test object to gpTestSubject will automatically add that subject to the test's subjects list). Then load test items (no need to load playlists): 
   test.load_items()
Now the items are loaded and you can start doing whatever you want with the results. (See functions' examples for examples)

2 · Functions for extracting information from the test

get_answers(list)
Returns a list of answers given to items in list (which can be a list of test items or a test object (which acts as a list)). The result list may contain 'None' items which means timeout/no answer.

get_times(list)
Returns a list of answer times from items in list. The result list may contain 'None' items which means timeout/no answer.

average(list)
Takes a list of numbers and returns a tuple (average, variance) calculated from the list.

2.1 · Examples

If you have first done as told in using test analysis class, you can now try some examples. (The >>> is python's promt.)

To get a list of answers (from a AB or ABX test): 

   >>> l1 = get_answers(test)
   >>> l1
   ['B', 'A', 'A', 'B', 'B', 'A', 'B', 'B', 'B', 'B', 'A', 'A', 'B', 'B',
   'A', 'B', 'A', 'A', 'A', 'A', 'B', 'A']
To get a list of answer times: 
   >>> l2 = get_times(test)
   >>> l2
   [7.81689, 33.9026, 3.33335, 0.929281, 5.49302, 4.14411, 1.92197,
    0.380971, 0.682314, 0.401833, 6.14924, 0.550957, 3.12145,
    0.402895, 31.0784, 0.585162, 20.4645, 0.393222, 5.42638, 0.423826,
    0.432659, 3.68162]
To calculate average and variance of l2: 
   >>> average(l2)
   (5.98712045455, 89.1919732625)
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