Stats

• Population


  the entire collection of individuals or objects about which information is desired. may be considered to be finite or infinite
• Census


  a collection of data from every member of the population
• Sample


  a sub-collection or subset of a population selected for study
• Parameter


  a numerical characteristic of a population
• Statistic


  a numerical characteristic of a sample
• Variable


  the characteristic about which we are interested
• Data


  the observations that have been collected
• Qualitative Data


  categorical or attribute data
• Quantitative Data


  numerical data
• Discrete Data


  count dataquantitative)
• Continuous Data


  measure dataquantitative)
• Sampling Error


  the difference between the result of a sample and the result for the entire population. caused by random fluctuations of the sample- i.e. by chance
• Normal


  bell-shaped distribution
• Statistically Significant


  observation that is extremely unlikely to happen simply by chance
• Descriptive Statistics


  the collection, presentation, and description of data
• Inferential Statistics


  interpreting the data in order to draw conclusions about the population, based on information obtained from a sample
• Frequency Distribution


  a chart or table giving the values of a variable together with their corresponding frequencies
• Blood Type


  example of a frequency distribution for qualitative data
• Class Width


  the difference between two consecutive lower class boundaries
• Class Midpoints


  the center value of each class
• Relative Frequency


  a proportional measure of frequency, calculated by dividing the frequency of that class by the total frequency of the data set
• Pie Chart


  a circular graph showing the relationships of parts to a whole, only one variable at a time may be displayed
• Bar Graph


  a rectangular graph representing quantities using heights of detached rectangles, generally used to display qualitative or discrete data, displays an ungrouped frequency distribution
• Histogram


  a rectangular graph representing quantities using heights of attached rectangles, used to display continuous data, displays a grouped frequency
• Elements of a Histogram

  a title, a horizontal scaleidentifying the variable), a vertical scaleidentifying frequencies)
• Stem and Leaf Display

  combines graphing and sorting the data, split into the leading digits, the trailing digits
• Outlier


  an unusually large or small data value with respect to its data set
• Dotplot


  a number line above which each data value is plotted as a point
• Measures of Central Tendency

  the middle or center of a data set, averages- mean, median, mode, midrange
• Averages


  mean, median, mode, midrange
• Arithmetic Mean


  adding the data values and dividing by the number of data values, balance point of a data set
• X Bar


  sample mean - statistic
• Mu


  population mean - parameter
• Median


  physical center of a data set
• Mode


  the most frequently occurring value in a data set
• Bimodal


  when two values occur with the same greatest frequency
• Midrange


  the value midway between the lowest and highest values in a data set, L+H/2
• Measures of Dispersion


  measure the spread or variability of the data set
• Range


  the difference between the largest and smallest values in a data set
• Standard Deviation


  the average distance of the data values from their mean