Frequency Distributions
Terms
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- *Frequency Distribution
- an organized tabulation (table or graph)of the number of individuals located in each category on the scale measurement. (a regular frequency distribution contains all the possible values of X and is usually arrnged from highest (top) to lowest (bottom).
- Grouped Frequency Distribution
- scores are groped into intervals rather than listed as individual values.
- Range
- the difference between the highest and lowest scores.
- Class Interval
- a group of scores in a grouped frequency distribution.
- Aparent Limits
- the score values that appear as the lowest and highest score in an interval
- Histogram
-
a graph showing a bar above each score or interval so that the (height/vertical) of the bar corresponds to the (frequency) and the (width/horizontal) extends to the real limits (values of the variable)
*used for ordinal. interval, or ratio data
*looks like bar graphs but the bars touch each other - Modified Histogram
- consists of stacks of blocks with each block representing one interval
- Bar Graph
- height of bar correspondes with frequency (space left between bars)
- Polygon
- a graph that consisted of lines that connest a series of dots that are placed above each interval so the height of the dot correspondes with frequency
- Relative Frequency (proportion,p)
- frequency reported in terms of the total number of scores.
- Relative Frequency Distribution
- displays the proportional (not exact) relationship of X values.
- Symmetrical Distribution
- a distribution where a graph of the distribution has a right-handed side that is a mirror image of the left-handed side
- Skewed Distribution
- a distribution where a graph of the distribution is not symmetrical
- Positively Skewed Distribution
- the scores pile up on the left side and taper off to the right.
- Negatively Skewed Distribution
- the scores pile up on the right side and taper off to the left
- Tail(s) of distribution
- a section on either side of a distribution where the frequency tapers down toward zero as the X values become more extreme
- Percentile
- a (score) that is described in terms of its percentile rank
- Percentile Rank
- a (percentage of individuals) with scores at or below the specific score
- Cumulative Frequency (cf)
- the (frequency of individuals) with scores at or below a specific score
- Cumulative Percentage (c%)
- the (percentage of individuals) with scores at or below a (particular point of distribution)
- Interpolation
- a mathematical procedure for (estimating a value) that is located (between two know values)
- Stem and Leaf Display
- a technique for (presenting a complete distribution of scores) in an (organized display) similar to a grouped frequency distribution table
- Nominal and ordinal data are displayed using _________ not __________.
- Bar graphs not Histograms
- Central Tendency
- a statistical measure where a single score defines the center of a distribution
- Mean
- the sum of the scores in a distribution divided by the number of scores
- Weighted Mean
- the sum of all the scores in more than one distribution divided by the TOTAL number if scores in the distribution
- Median
- the value that divides a distribution of scores exactly in half
- Mode
-
1.the score or catagory that had the greatest frequency
2.the scores that have distinctly higher frequences - Major Mode
- a score or category that has the absolute highest frequency
- Minor Mode
- a score or category that has a relatively high frequency
- Bimodal Distribution
- a distribution with two modes
- Multimodal Distribution
- a distribution with multiple modes
- Positive Skew
- a distribution where the graph of the distribution has a tail on the right side(+)
- Negative Skew
-
a distribution where the graph of the distribution has a tail on the left side
(-)