DATA ANALYSIS

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TUTORIAL

Positions: Least (L), Median (M), Greatest (G)

Q1=P25 Q2=M=P50 Q3=75

DATA ANALYSIS

Graphical Methods

Time Plots

Time Plots are used for showing changes in data collected in regular intervals of time.

Scatterplot

Scatterplots are used for bivariate data, to show the relationship between two numerical variables.
Trend line: overall pattern, slope. Calculated by substracting the G/L of y, and dividing it by G/L of x.

Histograms

Histograms are graphs of frecuency distribution; the values are grouped into intervals, each one having
a relative frecuency.

Circle Graphs

Bar Graphs

Bar Graphs with Multiple Variables

Segmented Bar Graphs

Numerical Methods

Measures of Dispertion

Standard deviation

Example

*Sample Standard Deviation: Mean of differences / n-1.

1) Calculate the mean 2) (Value of mean - each nº)2 3) Calculate the mean of differences 4) Possitive square root

Interquartile range

Q3 - Q1

Range

G-L

Measures of Position

Percentiles

Quartiles

Measures of Central Tendency

Mode

Number that occurs most frecuently in the list.

Median

Middle value of an ordered list of numbers.

Mean

The mean is the sume of n numbers divided by n. The weight of the value is the nº of times a value appears on the list