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31 Cards in this Set
- Front
- Back
Frequency Distribution
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organized tabulation of the number individuals located in each category on the SOM
- ranks and groups |
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Two Elements of a Frequency Distribution
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1. a set of categories that make up the original scale of measurement
2. a record of the number of individuals in each category (frequency) |
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Frequency Distribution Tables
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- simplest presentation style
- listing X(score) value categories (highest to lowest?) and recording frequency in adjacent column - x for scores - f for frequencies |
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X column in FDT represents?
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- SOM
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sigma f =
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N
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first step in sigma X +2...
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isolate x scores
ex 5 6 8 8 N= sigma f = 4 sigma x+2 = (5+2) + (6+2) + (8+2) + (8+2) sigma f/N= gives you the number of values if sigma f= 4 then 4 scores need to isolated and any further process acted upon them before summation |
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explaining f...
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- how many times a particular score event was reported (observed and measured)
- sigma f establishes the number of values reported by the FDT |
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x ... f... and f(x)...
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- x = score category(value category)
- f = number of times a specific score category was reported - f(x) - raw value of represented by score category and frequency in FDT |
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What are relative frequencies?
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- proportion of frequency compared to total frequency
- p = f/N |
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percentage
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- 100(f/n)
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How does group frequencies relate to the purpose of FDT?
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- relatively organized simple picture of data
- rather listing individual values grouping intervals can help for a concise presentation of data |
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Group Frequencies
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- groups of scores vs individual values
- this change effects x column labeling |
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What are Group Frequencies also called...
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class intervals
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Guidelines (ruleS) for FDT and class intervals
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1. approx 10 intervals
2. Simple Width (easily multiple sizes) 3. Bottom Score multiple of width scale 4. Interval Width Consistence (no gaps or overlaps // 1 score 1 interval) Range --> highest - lowest + 1 |
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Establishing Scalar Value
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range = highest - lowest +1
divided by 10 rounded to the nearest easily divisible number |
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Histogram
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- numerical scores (as categories) on x axis
- bar above the x value a. height - corresponding to the frequency or that category b. width - extends to real limits of the category |
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Polygons
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- ratio/interval
- numeric scores steps - dot centered above each category (height = frequency) - a continuous line connects dots - line extends below lowest score and above highest score |
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Steps for making Frequency Distribution Table:
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make list of each possible value from high to low
record frequency of each value on list figure percentage (or proportion) of scores for each value |
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Grouped Frequency
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- grouping values
- usng many possible values |
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Histogram
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- a bar chart
- for numerical scores - bars touch |
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two types of frquency distruibution graphs for numeric ratio and interval
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- polygons and historgrams
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Bar graph is for
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- nominal and ordinal scales
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Steps for creating a histogram:
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Make frequency table
List numerical scores along bottom from lowest to highest Make scale of frequencies along left edge starting from zero at bottom Make bar above each value with height for frequency of that value |
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Frequency Distribution Graph: Polygon
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Line graph
Line moves from point to point Height of each point shows number of scores with that value |
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relative frequency and smooth curves
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- large poulation ways of representing unaccounted data
- relative frequency of scores is a comparision of categories and smooth curve shows relative changes in scores with smooth line that dont cross over "real dots" |
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Three Characteristics that completely decribe any distribution:
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- shape, central tendency, variability
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variability
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- whether scores are clustered or spread out
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symmetrical distribution
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line down the middle creates two mirror images
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skewed distribution
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- distribution stacked on one side
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tail
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the direction in which the distribution tapers off
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whether a skewed graph is positive or negative dpends on ...
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- the direction of the tail...
- tail on lower limit side it is negatively skewed - tail on upper limit positively skewed |