Main Resource: Statistics Canada Website You have probably heard of the term the information age. It describes how modern society depends on information as a resource. People rely on information to make decisions and recommendations in many fields, including politics, economics, environment and entertainment. Without reliable information, people can make poor decisions that sometimes result in serious consequences. Since the media plays an immense part in our daily life and they are continually giving us information (data). Data analysis is often used in advertising, forecasting, and public policy. The media is full of representations of data (i.e. Graphs or tables) to support statistical claims. We need to be critical to: Know what is relevant Know what is important Know what is true Know what is biased Identify misinformation Etc. A graph is a visual representation of a relationship between, but not restricted to, two variables. Graphs are effective visual tools because they present information quickly and easily. It is not surprising then, that graphs are commonly used by print and electronic media. Circle graphs Line graphs Bar graphs Double bar graphs Pictographs A circle graph displays data as a percentage of the whole. Each pie section should have a label and percentage. A total data number should be included. A line graph plots continuous data as points and then joins them with a line. Multiple data sets can be graphed together, but a key must be used. A bar graph displays discrete data in separate columns. A double bar graph can be used to compare two data sets. Categories are considered unordered and can be rearranged alphabetically, by size, etc. A pictograph uses an icon to represent a quantity of data values in order to decrease the size of the graph. A key must be used to explain the icon. Misinterpretation is a common problem when using statistical information. It may be caused by a number of factors. Misunderstanding the data Using incomparable definitions Deliberately misinterpreting the information In groups of 2 or 3, come get a worksheet and answer the questions. You will need to prepare a short presentation about your topic (based on your worksheet) to present to the class. Advantages Visually appealing Shows percent of total for each category Disadvantages No exact numerical data Hard to compare 2 data sets "Other" category can be a problem Total unknown unless specified Best for 3 to 7 categories Use only with discrete data Advantages Can compare multiple continuous data sets easily Interim data can be inferred from graph line Disadvantages Use only with continuous data Advantages Visually strong Can easily compare two or three data sets Disadvantages Graph categories can be reordered to emphasize certain effects Use only with discrete data Advantages Easy to read Visually appealing Handles large data sets easily using keyed icons Disadvantages Hard to quantify partial icons Icons must be of consistent size Best for only 2-6 categories Very simplistic Look at the effect of not starting the y-axis of 0. It is important to start graphs at 0. Look at this pictograph. It looks like there are more horses. It is important that all the pictures are the same size. Why does Graph A look different than Graph B? Both the graphs represent the same data. The graphs look different due to the different vertical scales. Graph A appears to show a more rapid decrease in sales than graph B.
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