Basic StatisticsBasic Statistics

With a touch of ProbabilityWith a touch of Probability

Making DecisionsMaking Decisions

We make decisions based on the We make decisions based on the information we have. Statistics help information we have. Statistics help us examine the information so we us examine the information so we can make educated decisions vs. can make educated decisions vs. “guessing” or gut feelings. “guessing” or gut feelings.

Should I climb Mt Everest?Should I climb Mt Everest?

Not Me!Not Me!

As of the end of the 2004 climbing season </wiki/As_of_2004>, 2,238 people had reached the summit (1,148 of them since 1998) and 186 people died while summitting. The conditions on the mountain are so difficult that most of the corpses have been left where they fell; some of them are easily visible from the standard climbing routes.

What is Statistics?What is Statistics?

Statistics is the study of how to Statistics is the study of how to collect, organize, analyze, and collect, organize, analyze, and interpret numerical information from interpret numerical information from data.data.

Vocabulary for StatisticsVocabulary for Statistics

Population – The entire group of Population – The entire group of interest. interest.

Individual – people or objects in the Individual – people or objects in the population.population.

Sample - a part of the population.Sample - a part of the population.

VariableVariable

Characteristic of the individual to be Characteristic of the individual to be measured or observed.measured or observed.

Two Kinds of VariablesTwo Kinds of Variables

Quantitative – has value or numerical Quantitative – has value or numerical measurement for which operations such measurement for which operations such as addition or averaging make sense. as addition or averaging make sense. Exp. Average height of BKB players Exp. Average height of BKB players

Qualitative – describes an individual by Qualitative – describes an individual by placing the individual into a category or placing the individual into a category or group (categorical) Exp. Male or femalegroup (categorical) Exp. Male or female

4 levels of measurement4 levels of measurement

1. Nominal – name only. Can not 1. Nominal – name only. Can not compare among data. (JW, ACCHS, Sab) compare among data. (JW, ACCHS, Sab) names of league schoolsnames of league schools

2. Ordinal – some order of variables but 2. Ordinal – some order of variables but no data values. Exp. Good, fair, poorno data values. Exp. Good, fair, poor

3. Interval – like ordinal, but have values 3. Interval – like ordinal, but have values with no clear start or zero. Exp temp of with no clear start or zero. Exp temp of studentsstudents

4. Ratio – like interval but has start or 4. Ratio – like interval but has start or zero. Can calculate a ratio.zero. Can calculate a ratio.

Two Types of StatisticsTwo Types of Statistics

Descriptive Statistics – Organize, Descriptive Statistics – Organize, picturing, and summarizing picturing, and summarizing information from samples or information from samples or populations.populations.

Inferential Statistics – method of Inferential Statistics – method of using information from a sample to using information from a sample to draw conclusions regarding a draw conclusions regarding a population.population.