Histograms: Bar graphs that show the frequency distribution of continuous data.
Example: A histogram can show the distribution of heights of students in a class.
Frequency Polygons: Line graphs that connect the midpoints of the tops of the bars in a histogram.
Example: A frequency polygon can show the distribution of test scores in a class.
Line Diagrams: Used to show trends over time, such as population growth or stock prices.
Example: A line diagram can show the change in temperature over a week.
Pie Charts: Circular charts that show the proportion of different categories within a data set.
Example: A pie chart can show the percentage of students who prefer different subjects.
Pictograms: Use pictures or symbols to represent data.
Example: A pictogram can use car symbols to represent the number of cars sold each month.
Tally Charts: A simple way to count and record data using tally marks.
Example: A tally chart can be used to count the number of red, green, and blue cars in a parking lot.
Stem-and-Leaf Plots: A method of organizing data to show its distribution.
Example: A stem-and-leaf plot can show the distribution of test scores, with the tens digit as the stem and the ones digit as the leaf.
Box-and-Whisker Plots: A graphical representation of the five-number summary: minimum, first quartile, median, third quartile, and maximum.
Example: A box-and-whisker plot can show the distribution of house prices in a neighborhood.
Statistical Maps: Use maps to visualize geographical data.
Example: A statistical map can show the population density of different countries.
Statistical Averages
To summarize data, we often calculate statistical averages:
Mean (Arithmetic Mean): The sum of all values divided by the number of values.
Formula: Mean = (Sum of all values) / (Number of values)
Example: If the scores on a test are 8, 10, 12, and 14, the mean is (8+10+12+14)/4 = 11.
Median: The middle value when data is arranged in order.
Example: For the scores 8, 10, 12, and 14, the median is (10+12)/2 = 11.
Mode: The most frequently occurring value.
Example: In the data set 2, 3, 3, 4, 5, 6, 6, 6, the mode is 6.
Range: The difference between the highest and lowest values.
Formula: Range = Highest value - Lowest value
Example: For the scores 8, 10, 12, and 14, the range is 14-8 = 6.
Mean Deviation: The average of the absolute deviations from the mean.
Formula: Mean Deviation = Σ|x - x̄| / n
Example: For the scores 8, 10, 12, and 14, the mean deviation is (|8-11| + |10-11| + |12-11| + |14-11|) / 4 = 1.
Standard Deviation: A measure of how spread out numbers are.
Formula: Standard Deviation = √(Σ(x - x̄)² / n)
Example: For the scores 8, 10, 12, and 14, the standard deviation is approximately 2.16.