Christopher Pouncy's List: STATISTICS

• Graphs or charts help people understand data quickly.
• When you come to plot data, the known value goes on the x-axis and the measured (or "unknown") value on the y-axis.
• Line Graphs
• Trend data:
• Correlation:
• You can only use line graphs when the variable plotted along the x-axis is continuous – for example, time, temperature or distance.
• When the y-axis indicates a quantity or percent and the x-axis represents units of time, the line graph is often referred to as a time series graph.
• It's easy to compare trends when they're represented on the same graph.
• Bar Graphs
• Often the choice comes down to how easy the trend is to spot

  • Whether Line or Bar graph. Whichever one is easiest to read and analyze.
• Figure
• Data can also be represented on a horizontal bar graph as shown in Figure 7.

  • So you can reverse the process and put the x-axis in a vertical position as well as putting the y-axis horizontally.

• Tip 1:

   

  Be careful not to use too many segments in your pie chart. More than about six and it gets far too crowded. Here it is better to use a bar chart instead.

• ip 2:

   

  If you want to emphasize one of the segments, you can detach it a bit from the main pie. This visual separation makes it stand out.
• The last graph we will cover here is the Venn diagram. Devised by the mathematician John Venn in 1881, this is a diagram used to show overlaps between sets of data.

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• The “index” shows how an individual site’s audience compares to the internet population as a whole. For example, an index of 100 indicates a site’s audience is equivalent to the demographic make-up of the total internet population. Any number over 100 means that the property is “over indexed” and attracts a more concentrated group of a particular demographic group than in the general internet population.

• When one of Skinner's rats pressed a lever, it was given a food pellet. By experiment Skinner then established that if a pellet was delivered only on the 10th press of the lever, the rat would quickly learn to press the lever 10 times.
• If, however, a random element was introduced to the lever-pressing, whereby a pellet was still introduced on average one in 10 times, but sometimes delivered twice or three times in a row and sometimes not for 20 or more presses, the rat apparently became obsessed with the lever-operation itself.

• The rats on a fixed one-in-10 schedule only pressed their levers when they were hungry, confident that the food would arrive when they needed it; the rest of the time they got on with their rat lives. The rats on the variable schedule, by contrast, stood almost constantly by the lever, pressing furiously, mesmerised by the uncertainty of delivery, apparently hoping to work out the system, or hit the three-in-a-row pellet jackpot.
• Gloria Steinem once observed that 'women's total instinct for gambling is satisfied by marriage'; in Britain that no longer applies.
• 1931 Nevada legalises casino gaming.
• 1946 Benjamin 'Bugsy' Siegel opens the Flamingo hotel and casino. He is assassinated in 1947 by his fellow mafiosi for running up huge debts.
• 1980s Corporate gambling comes of age, as mass-marketing techniques are employed to sell it as family entertainment. Las Vegas becomes known as 'Disneyland for adults'.
• 1992 Akio Kashiwagi, a Tokyo-based gambler who had once won more than $6m at Atlantic City's Trump Plaza, loses close to $10m in six days at a baccarat table. The following year he is stabbed to death in his home at the foot of Mount Fuji.
• The Winning Odds: pounds 8 on a fruit machine: 600/1; pounds 50,000 scratch-card jackpot: 2.57 million/1; top prize on the Lottery: 14.5 million/1.

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