# Frequency Distributions & Graphs

Frequency Distributions & Graphs Wed, Feb 11th, 2004 Frequency Distributions Organize data into a table showing # observations in each category Includes category, its frequency (f), and its proportion (P) Proportion (P) = f / N (total sample size) Score f P 10

32 .31 9 45 .43 8 27 .26 Total 104 (cont.) If too many categories, use grouped freq distribution (you decide the appropriate class interval) Exam Score 90-100 80-89

70-79 Total f 12 15 8 35 % 34.3% 42.9% 22.8%

100% (cont.) May prefer Cumulative Distributions to show cumulative freq or prop/%: Show f or p at or below each category (label cf or cp) Add f or p for each category to total f or p for all previous categories Score f P cf cP

10 32 .31 104 1.00 9 45 .43 72 .69 8 27 .26 27 .26 Total 104 Graphs Bar chart shows frequency of nominal/ ordinal variables. Indicates frequency or % on y axis,

categories on x axis; bars do not touch Example: Histogram shows frequency of interval/ratio variables Frequency or % on y axis, order values from low to high on x axis; bars touch Example: (cont.) Frequency polygon same as histogram, but instead of bars, use points at midpoint, connect w/lines

Time Series Chart is similar w/time on x axis Examples: Shapes of Distributions Examine histogram, bar graph, look at overall shape: Bell-shaped distribution most scores in middle; fewer at extremes Positively skewed distribution: most scores at low end of scale, tail of distribution points to high (pos) end Negatively skewed distribution: most

scores at high end of scale, tail points to low (neg) end of scale A note on HW4 HW4 due Monday Ch 2 # 1, 6, 10, 13 and SPSS problems 1a-1d (all parts of #1) and 3a & 3b at end of ch 2 Youll need the data GSS98PFP-A to do the SPSS hw problems If you have the book CD-rom, its on there if not, let me know now and Ill email you the data file.

SPSS -Graphs Use student.sav data in link in lab Use menus at top: For tables, use Analyze Descriptive Statistics Frequencies Then indicate variables you want in table, hit OK Switches to output window Switch back to data view to do more analyses SPSS (cont.)

For graphs, use menu Graph, then bar graph or histogram Examine shapes of these distributions NOTE: skip Stem & Leaf Plot section of the lab and #12

## Recently Viewed Presentations

• It has ambitious objectives for 2020 - to improve efficiency (by halving the unit cost of ATM), to improve capacity (by tripling it), to improve safety (tenfold) but also to improve ATM environmental performance by reducing emissions per flight by...
• WASTE RECYCLING offered services MODULAR TECHNOLOGY FOR THE RECYCLING PLASMA AND LCD SCREENS elaborated at the AQUATEST a.s. workshop in Mníšek pod Brdy, Czech republic is designed as a modular system of individual technological parts which can be changed based...
• Horrendous. is shockingly dreadful. Humiliate. is to cause a loss of pride or dignity. Humongous. means extraordinarily large. Hurrah. is an exclamation of joy. Hustle. is to proceed or work rapidly. Hyacinth. is a plant of the lily family. Hybrid....
• The Landlady By Roald Dahl Objective: I will use knowledge of vocabulary, setting and the literary element of foreshadowing to analyze fictional text. Vocabulary Read each sentence. Try to understand the definition of each word based on the context clues....
• Top 10 Most Cited OSHA Standards Violations in FY13. 1. Fall protection, construction (29 CFR 1926.501) [related OSHA Safety and Health Topics page] 2. Hazard communication . standard, general industry (29 CFR 1910.1200) [related OSHA Safety and Health Topics page]...
• Othello, fastidiously explore the intellectual predicaments faced by their subjects and the fine nuances of their subjects' characters, Macbeth tumbles madly from its opening to its conclusion. It is a sharp, jagged sketch of theme and character; as such, it...
• For example a checklist for Fundulus heteroclitus (Hoffman, 1999) indicates that they are parasitized by 12 protozoa, seven monogenea, nine trematoda, two cestoidea, four nematoda, three acanthocephala, and five crustacea.
• Chinook and coho are also counted as either adults or jacks, based on length. ... Both the NOAA Fisheries BiOp and the Northwest Power Planning Council (NPPC) Fish and Wildlife Program establish regional processes for fish passage management.