Class: JLDrill::Statistics

Inherits:
Object
  • Object
show all
Defined in:
lib/jldrill/model/Quiz/Statistics.rb

Overview

Statistics for a quiz session

Constant Summary collapse

MINIMUM_CONFIDENCE = 
0.009
SECONDS_PER_DAY = 
60 * 60 * 24

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(quiz, binNumber) ⇒ Statistics

Returns a new instance of Statistics.



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 21

def initialize(quiz, binNumber)
    @quiz = quiz
    @binNumber = binNumber
    @estimate = 0
    @correct = 0
    @incorrect = 0
    @lastTen = []
    @inTargetZone = false
    @timesInTargetZone = 0
    @levels = []
    1.upto(8) do
        @levels.push(LevelStats.new)
    end
    @learned = 0
    @reviewed = 0
    @reviewRateSum = 0
    @reviewTimer = Timer.new
    @learnTimer = Timer.new
    @currentTimer = nil
    resetConfidence 
end

Instance Attribute Details

#confidence ⇒ Object (readonly)

Returns the value of attribute confidence.



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 13

def confidence
  @confidence
end

#estimate ⇒ Object (readonly)

Returns the value of attribute estimate.



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 13

def estimate
  @estimate
end

#lastTen ⇒ Object (readonly)

Returns the value of attribute lastTen.



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 13

def lastTen
  @lastTen
end

#learned ⇒ Object

Returns the value of attribute learned.



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 13

def learned
  @learned
end

#levels ⇒ Object (readonly)

Returns the value of attribute levels.



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 13

def levels
  @levels
end

#reviewed ⇒ Object

Returns the value of attribute reviewed.



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 13

def reviewed
  @reviewed
end

#timesInTargetZone ⇒ Object (readonly)

Returns the value of attribute timesInTargetZone.



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 13

def timesInTargetZone
  @timesInTargetZone
end

Instance Method Details

#accuracy ⇒ Object

Returns the actual % accuracy of the quiz in an integer



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 174

def accuracy
    retVal = 0
    if @incorrect == 0
        if @correct != 0
            retVal = 100
        end
    else
        retVal = ((@correct * 100) / total).to_i
    end
    retVal
end

#averageReviewRate ⇒ Object 



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 105

def averageReviewRate
    retVal = 1.0
    if @reviewed != 0
        retVal = ((@reviewRateSum * 10).round / @reviewed).to_f / 10 
    end
    return retVal
end

#calculateConfidence(wasCorrect) ⇒ Object

Calculates a Bayesian estimate (I think!) of the confidence that the items seen to this point were known to an accuracy of at least 90%.

How this is calculated:

 According to Bayes law, P(H|E) = P(E|H) * P(H) / P(E)
 Where:
    P(H|E) is the probability that the hypothesis is correct
           given the evidence.  
    P(E|H) is the probability that the evididence would be
           shown if the hypothesis were correct.
    P(H)   is the probability that the hypothesis is correct
           given any evidence.
    P(E)   is the probability that the evidence would be seen
           in all cases.

This value is calculated incrementally in the following fashion:
    P[n] = P(E|H) * P[n-1] / P(E)
i.e., the nth value of P is dependent on the n-1th value of P

In our case, I will assume that the distribution of the 
probabilities is uniform (probably wrong!) and say that
if we got the question right
     P(E|H) = 0.95 
          that is, our probability of getting it right is
          somewhere between 90 and 100%.  I assume uniform
          distribution, therefore the average is in the middle.
or if we got the question wrong
     P(E|H) = 0.05
          obviously, the probability of getting it wrong given
          the hypothesis is 1 minus the probability of getting
          it right.
     P(E) = sum(probabilities for all the hypotheses)
          = P(chance < 90) + P(chance is 90+%)
     P(chance < 90) = 0.45(1 - P[n-1])
          that is, it's equal to 1/2 the range between 0 and 90
          times the probability that hypothesis is wrong.
     P(chance > 90) = 0.95P[n-1]
          that is, it's equal to 1/2 the range between 90 and 100
          times the probability that the hypothesis is right.
          So...
     P(E) = 0.45(1 - P[n-1]) + 0.95P[n-1]

 Giving a final answer of
     P[n] = P(E|H) * P[n-1] / (0.45(1 - P[n-1]) + 0.95P[n-1])

 I fully expect this is completely wrong due to my lack of
 ability in math and statistics.  But on the other hand, I won't
 care much as long as appears from the user's point of view to
 be working.



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 249

def calculateConfidence(wasCorrect)
    if wasCorrect
        pEH = 0.95
    else
        pEH = 0.05
    end
    pE = (0.45 * (1.0 - @confidence)) + (0.95 * @confidence)
    @confidence = (pEH * @confidence) / pE
    if @confidence < MINIMUM_CONFIDENCE
        @confidence = MINIMUM_CONFIDENCE
    end
end

#correct(item) ⇒ Object 



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 131

def correct(item)
    if item.bin != @binNumber
        return
    end
    @correct += 1
    @reviewed += 1
    recordReviewRate(item)
    level = getLevel(item)
    if !level.nil?
        level.correct
    end
    record(true)
    reEstimate
    calculateConfidence(true)
end

#correct=(value) ⇒ Object 



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 163

def correct=(value)
    @correct = value
    reEstimate
end

#currentReviewRate ⇒ Object 



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 113

def currentReviewRate
    retVal = 1.0
    if size > 0
        rate = reviewBin[0].schedule.reviewRate
       retVal = ((rate * 100).round).to_f / 100
    end
    retVal
end

#getLevel(item) ⇒ Object

Get the appropriate LevelStat object for this item



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 89

def getLevel(item)
    return @levels[Counter.getLevel(item)]
end

#incorrect(item) ⇒ Object 



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 147

def incorrect(item)
    if item.bin != @binNumber
        return
    end
    @incorrect += 1
    @reviewed += 1
    recordReviewRate(item)
    level = getLevel(item)
    if !level.nil?
        level.incorrect
    end
    record(false)
    reEstimate
    calculateConfidence(false)
end

#incorrect=(value) ⇒ Object 



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 168

def incorrect=(value)
    @incorrect = value
    reEstimate
end

#inTargetZone? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 70

def inTargetZone?
    # Don't start the countdown until we have reviewed
    # at least 10 item.
    if @reviewed <= 10
        return false
    end
    if !@inTargetZone
        if recentAccuracy >= 90
            @inTargetZone = true
        end
    else
        if (recentAccuracy < 90) && (@confidence < 90)
            @inTargetZone = false
        end
    end
    return @inTargetZone
end

#learnPace ⇒ Object 



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 293

def learnPace
    if @learned > 0
        roundToOneDecimal(learnTime / @learned)
    else
        0.0
    end
end

#learnTime ⇒ Object 



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 278

def learnTime
    @learnTimer.total
end

#learnTimePercent ⇒ Object 



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 309

def learnTimePercent
    total = learnPace + reviewPace
    if total > 0
        ((learnPace * 100) / total).to_i
    else
        0
    end
end

#recentAccuracy ⇒ Object 



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 57

def recentAccuracy
    retVal = 0
    if @lastTen.size > 0
        0.upto(@lastTen.size) do |i|
            if @lastTen[i]
                retVal += 1
            end
        end
        retVal = (retVal * 100 / @lastTen.size).to_i
    end
    retVal
end

#record(bool) ⇒ Object

Record a result. True means that the item was guessed correctly, false means it was incorrect.



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 45

def record(bool)
    @lastTen.push(bool)
    while @lastTen.size > 10
        @lastTen.delete_at(0)
    end
    if inTargetZone?
        @timesInTargetZone += 1
    else
        @timesInTargetZone = 0
    end
end

#recordReviewRate(item) ⇒ Object 



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 93

def recordReviewRate(item)
    @reviewRateSum += item.schedule.reviewRate
end

#reEstimate ⇒ Object

Generates an estimate of the % accuracy in an integer



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 191

def reEstimate
    hop = ((recentAccuracy - @estimate) * 0.3).to_i
    retVal = @estimate + hop
    if (retVal > 100) then retVal = 100 end
    if (retVal < 0) then retVal = 0 end
    @estimate = retVal
end

#resetConfidence ⇒ Object 



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 262

def resetConfidence
    @confidence = MINIMUM_CONFIDENCE
end

#reviewBin ⇒ Object 



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 97

def reviewBin
    return @quiz.contents.bins[@binNumber]
end

#reviewPace ⇒ Object 



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 301

def reviewPace
    if @reviewed > 0
        roundToOneDecimal(reviewTime / @reviewed)
    else
        0.0
    end
end

#reviewTime ⇒ Object 



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 282

def reviewTime
    @reviewTimer.total
end

#roundToOneDecimal(value) ⇒ Object 



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 286

def roundToOneDecimal(value)
    value = value * 10.0
    value = value.round
    value = value.to_f / 10.0
    value
end

#size ⇒ Object 



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 101

def size
    return reviewBin.length
end

#startTimer(isReview) ⇒ Object 



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 266

def startTimer(isReview)
    if !@currentTimer.nil?
        @currentTimer.stop
    end
    if isReview
        @currentTimer = @reviewTimer
    else
        @currentTimer = @learnTimer
    end
    @currentTimer.start
end

#statsTable ⇒ Object 



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 122

def statsTable
    dCounter = DurationCounter.new

    reviewBin.each do |item|
        dCounter.count(item)
    end
    return dCounter
end

#total ⇒ Object 



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# File 'lib/jldrill/model/Quiz/Statistics.rb', line 186

def total
    @correct + @incorrect
end