spread

(noun)

A numerical difference.

Related Terms

Examples of spread in the following topics:

  • Student Learning Outcomes

    • Recognize, describe, and calculate the measures of the spread of data: variance, standard deviation, and range.

  • Range

    • The range is a measure of the total spread of values in a quantitative dataset.
    • In statistics, the range is a measure of the total spread of values in a quantitative dataset.
    • For example, if you read that the age range of two groups of students is 3 in one group and 7 in another, then you know that the second group is more spread out (there is a difference of seven years between the youngest and the oldest student) than the first (which only sports a difference of three years between the youngest and the oldest student).

  • Practice 2: Spread of the Data

  • Properties of Sampling Distributions

    • Finally, the variability of a statistic is described by the spread of its sampling distribution.
    • This spread is determined by the sampling design and the size of the sample.
    • Larger samples give smaller spread.
    • As long as the population is much larger than the sample (at least 10 times as large), the spread of the sampling distribution is approximately the same for any population size

  • Measures of Variability

    • Variability refers to how "spread out" a group of scores is.
    • To see what we mean by spread out, consider graphs in Figure 1.
    • Specifically, the scores on Quiz 1 are more densely packed and those on Quiz 2 are more spread out.
    • The terms variability, spread, and dispersion are synonyms, and refer to how spread out a distribution is.
    • Using this terminology, the interquartile range is referred to as the H-spread.

  • Homogeneity and Heterogeneity

    • By drawing vertical strips on a scatter plot and analyzing the spread of the resulting new data sets, we are able to judge degree of homoscedasticity.
    • When various vertical strips drawn on a scatter plot, and their corresponding data sets, show a similar pattern of spread, the plot can be said to be homoscedastic.

  • Practice 1: Center of the Data

    • The student will calculate and interpret the center, spread, and location of the data.
    • Looking at your box plot, does it appear that the data are concentrated together, spread out evenly, or concentrated in some areas, but not in others?

  • Graphing the Normal Distribution

    • Mean specifically determines the height of a bell curve, and standard deviation relates to the width or spread of the graph.
    • In order to picture the value of the standard deviation of a normal distribution and it's relation to the width or spread of a bell curve, consider the following graphs.

  • Variance

    • When describing data, it is helpful (and in some cases necessary) to determine the spread of a distribution.
    • When determining the spread of the population, we want to know a measure of the possible distances between the data and the population mean.

  • Measures of the Spread of the Data

    • The most common measure of variation, or spread, is the standard deviation.
    • The deviations show how spread out the data are about the mean.
    • The standard deviation measures the spread in the same units as the data.
    • The reason is that the two sides of a skewed distribution have different spreads.
    • The spread of the exam scores in the lower 50% is greater (73 - 33 = 40) than the spread in the upper 50% (100 - 73 = 27).