STATISTICS

Some vocab

Statistics is the art of solving problems and answering questions by collecting and analysing data.

Data are the facts or information we collect and analyze. (plural)

(note datum is the singular term) Data set- a list of unorganized data. Often called the

raw data

Raw Data

.....just the numbers

Statistical Investigation

Step 1: Examining a problem which might be solved using data and asking questions (how many students ride bikes to school)

Step 2: Collecting the data Step 3: Organising the data. Step 4: Summarising and displaying the data. Step 5: Analysing the data, and making a conclusion Step 6: Writing a report (presenting your findings)

Census/Sample

A census is a method which involves collecting data about EVERY individual in a whole population.

A sample is a method which involves collecting data about a part of the population. Not as detailed or accurate as census,

but easier.

Problems with a sample

A sample can be biased if the data has been unfairly influedned in the collection process. A biased sample won’t represent the whole population

Question: Are you good at climbing trees?

Other problems

Question: Do Americans like cheese burgers???

I am American. I like cheese burgers. There fore ALL Americans like cheeseburgers. Valid argument?!?! Could use Logic!

A sample must be sufficiently large to represent the whole population

Variables in Statistics

Categorical variable – describes qualities or characteristics. Can be divided into categories.

The information is called categorical data.

Examples. Getting to school: Bus, train, bike, car, walking. Color of eyes:

Variables in statistics

Quantitative variable- has a numerical value, and is often called a numerical variable.

The information collected is called numerical data. Can be discrete or continuous. A quantitative discrete variable takes exact number

values. (Think counting) Examples. Number of people in a house hold The score out of 30 on a test The number of sunny days in Stavanger. 1,2,3,4,.....

Variables in Statistics

A quantitative continuous variable takes numerical values within a certian CONTINOUS range. (think measuring)

Examples. The weights of new born babies The heights of 9th grade students Time

What do you think?

Classify the following variables as categorical, quantitative discrete, or quantitative continous.

A. The brand of shoes a person wears B. The number of cousins a person has C. The temperature of my coffee D. The number of cars a household owns E. The voting intention at the next election F. Cost of houses on a street G. Height of 11th graders H. Favorite type of food I. Town or city where a person was born

Presenting and Interpreting Categorical Data

What is the PERCENTAGE of the pie I have eaten (estimate)

Presenting and Interpreting Numerical Data Freqency= number of times the data

occurs Mode= most frequently occuring

data

Presenting and Interpreting Data

Presenting and Interpreting Data

Presenting and Interpreting Data

The Distribution of Data

(going to lunch)

Outliers

Interesting Statistics

http://www.worldometers.info/ http://www.informationisbeautiful.net

/visualizations/

http://www.babynamewizard.com/voyager#ms=false&exact=false

http://news.bbc.co.uk/2/hi/science/nature/7137462.stm