The field of statistics deals with the collection, presentation, analysis, and use of data to make decisions and solve problems.

Statistical techniques can be used to describe and understand variability.

IME 301

Inferential statistics makes a decision about a particular population.

Descriptive statistics are methods for organizing and summarizing data.

Population refers to the collection of measurements on all elements of a universe about which we wish to draw conclusion or make decisions.

Sample is just a subset of observations selected from the population

IME 301

Data SummaryData Display and Graphical Methods: bar chart, pie chart, histogram

Measure of central tendencysample mean, sample median, population mean, mode

Measure of spread (variability)sample range, sample variance, sample standard deviation,population variance, quartile, inter-quartile

Data Display and Graphical Methods, cont.: box plot, frequency distribution, relative frequency histogram, time plot

IME 301

Mean Variance

Sample

Population

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ni

i i

1

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)(1

22

n

xxS

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i i

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i i

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Size

n

N

IME 301, Sept 98