Workshop 2008: Weblog for Maths (Sec) Activity 7a

Instructions

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2008-02-14T16:39:00.001+08:00

Comments, anyone?

Lies, Damned lies and Statistics

2008-02-14T16:33:00.001+08:00

Shall we talk about it?

Data for comparison

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Pie charts are used to represent a single data for comparison(upon 100% or 360 degrees), for example the percentage of people who are of different race; eg. Chinese, Malay, Indian, Eurasian. others.

Is there that much of a difference?

2008-02-14T16:31:00.010+08:00

Perhaps it's up to how you want to manipulate the data.

They both represent categorical data.
But...
Bar charts show the "little" differences in proportion between the categories. The different segments in a pie chart do not show marked differences especially if the proportions vary only slightly.

Longer is better then Bigger?? =)

2008-02-14T16:31:00.008+08:00

Pie charts are actually a poor method of displaying information.

One reason for this is that it is more difficult for comparisons to be made between the size of items (the slice of *cake*) accurately in a pie chart.

Hence for statistics with many data... use a Bar Chart instead. Comparing of length is easier. =)

pie chart?

2008-02-14T16:30:00.003+08:00

When we just want to make comparisons at glance where each sector already clearly show what they represents, especially when the actual values may not be that important.

Activity 7a

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Use pie chart to represent the students population based on their ethnic groups
Use bar chart to represent the number of students in different CCA

i love Pies!

2008-02-14T16:29:00.005+08:00

Pie chart- When u want to calculate and depict the percentage of each segment over the whole, can be done more easily and readily.

Pie charts

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Pie charts are often used for a single set of data with a few items. The total percentage of the sectors must add up to 100%. It is important for the percentage to be shown for each sector and that the size of the sector should reflect (roughly, at least) the percentage.

Bar charts are useful when used with two or even three sets of data for comparision.

Use pie chart only when we have a few data

2008-02-14T16:28:00.007+08:00

We can't possibly represent 50 readings in a pie chart right? it's too crammed!

What is best as a pie chart?

2008-02-11T09:26:00.000+08:00

More useful for comparing/presenting a small quantity of discrete data. As it will be used to express the total (100%) as a full circle of 360 degrees, fractions may be a chore. Tell it as it is!
On the contrary, bar charts are the statistician's greatest tool. It allows for the sensationalising findings or "playing down" findings through the use of well-chosen scales. Tweak it??