PBL

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PBL 2 Group 3 (T7C)

• ByLeung Chung Nin, Kenny
• Chiu Chun Ho, Terence
• Yiu Chin Wang, Alex
• Wan Po Lam, Vicky

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Introduction

• Case study of counting people in July 1 rally
• Comparison of 3 different methods
• Best method
• Improvements

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Method by Civil Human Rights Front

• Based on the capacity of the designated route
• Measure the time required
• Estimated Number of people
• Capacity x Time elapsed

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170,000 people
Start
End
Take 1.5 hours to finish
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Comments

• Advantage
• Easy to obtain
• Disadvantages
• Many unknown and variable factors
• e.g. 1) concentration of the crowd
• 2) speed of walking
• 3) people joining or leaving
• Figure obtained will not be precise if the error
  is multiplied by time taken
• Just a rough estimate by capacity

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Method by Robert Chung Ting-Yiu

• Set up 6 headcounts
• 1 minute count every 5 minutes
• Count number of people who passed through
  checkpoints
• Figures adjusted according to survey

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Comments

• Advantage
• Have Real Time data (quick response)
• Disadvantages
• Limiting Factors of checkpoints
• e.g. 1) Fixed locations
• 2) Limited number
• Ignore the number of people who joined or left in
  between
• Not Accurate Enough

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Method by HKU social sciences research centre

• 2 video cameras taking record
• 4 seconds of footage studied every 30 seconds
• Number of people counted in video

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Comments

• Advantages
• Video record can be used again
• Different samples can be drawn
• Disadvantages
• The most costly method
• Time-consuming
• Fixed location
• Real time data can not be obtained easily

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Question should be includes in the questionnaire

• 1. Where did you join the rally?
• 2. When did you join the rally?
• 3. Which checkpoint did you pass through?

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Method of estimation

• Total no of people joined in mid way
• Proportion of people joined in mid way X
• no of people counted by checkpoint

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Conclusion

• Method 2?Best!!!!
• Less costly
• No need to multiply
• ? reduce error

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Improvements

• Increase number of check points
• ?reduce distance between checkpoints

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Real life situation

• Urgent
• ?Method 1
• High accuracy
• ?Method 2/3