Practical Uses of Statistics
      Poll results are used to determine the television shows we 
       watch and the products we purchase.
      Manufacturers provide better products at lower costs by 
       using statistical control tools, such as control charts.
      Diseases are controlled through analyses designed to 
       anticipate epidemics.
      Endangered species of fish and other wildlife are 
       protected through regulations and laws that react to 
       statistical estimates of changing population sizes.
      Through statistical analysis of fatality rates, legislators 
       can better justify laws, such as those governing air 
       pollution, auto inspections, seat belt and air bag use, and 
       drunk driving.
     These are just a few examples of the many practical uses of 
     statistics!
           Abuses of Statistics
     Some people will use statistics in which the data 
       are presented in ways that are designed to be 
       misleading.
     Some abuses are not intentional, but some are!
        “Statistics show far fewer skateboarding 
         injuries in the winter, while sledding 
         injuries are more common.”
         Does this seem like a valid statement?  What 
          could be a reason for such misleading 
          statistics?
     Abuses of Statistics (continued)
      Common ways in which data are misleading:
       1) Bad samples
         A major source of deceptive statistics is the 
          use of inappropriate methods to collect data.
         Self-selected survey – (voluntary response 
          sample) is one in which the respondents 
          themselves decide whether to be included
           In such surveys, people with strong 
            opinions are more likely to participate, so 
            the obtained responses are not 
            necessarily representative of the whole 
            population.
     Abuses of Statistics (continued)
      Common ways in which data are misleading:
       2) Small Samples
          It can be very misleading to make broad 
          conclusions or inferences based on samples 
          that are far too small.
           Example: Children’s Defense Fund’s 
            publication of Children Out of School in 
            America reported that among secondary 
            school students suspended in one region, 
            67% were suspended at least three times. 
            That statistic was based off of only three 
            students, and the media reports failed to 
            mention that!
         Abuses of Statistics (continued)
        Common ways in which data are misleading:
          3) Loaded Questions
             Survey questions can be worded to elicit a desired response.
              A “loaded” item uses emotionally charged words – words 
               that have a strong negative or positive. 
                 Example: The University of Pittsburgh should stop 
                  wasting student activities funds on elitist organizations 
                  such as fraternities and sororities. 
                          A. strongly agree 
                          B. agree 
                          C. neutral 
                          D. disagree 
                          E. strongly disagree 
                   
                     This is a loaded item because of the use of the 
                    phrases “wasting funds” and “elitist organizations.” It 
                    would be improved by making the wording more 
                    neutral.