Statistics! Unit 8 Day 1

Statistics Statistics – is a collection of data that provides information.   We can either collect data from: Population – the entire group of individuals or objects we are studying Sample – a proportion of the entire group A specific question/quantity we want to know from the population is called, a parameter. A specific question/quantity we want to know from the sample is called, a statistic.

Examples Ms. Thompson ask her Math III students what music they listen to in order to determine what the entire student population prefers.   Adam surveyed 500 people to determine what percentage of people who dream in color.  Kelly polled residents living in Iredell County to determine who North Carolina would vote for presidency.

More on Sample Data (Important!) When collecting data from a sample, each member from the population must have an equal chance of being chosen. Why? So the sample provides a true representation (or correlation) of the population allowing us to predict the entire population’s results. This is also known as statistical inference. How? By taking a large number of random samples of the population to eliminate bias. Types of Bias: Convenience Voluntary Personal choice Leading questions Placebo effect

Read the following scenarios and determine the type of bias presented. Those who agree to participate in a study to earn $100. A doctor gives their patience a sugar pill telling them that it will help their anxiety. Ms. Thompson took a sample from her Math III class to represent the population of the entire student population at Lake Norman. Enlighten of immigrant issue, who would you vote for presidency? You choose to ask your friends questions for a study.

Methods of Sampling Random – Selected by using chance. Everyone has an equal opportunity of being chosen. Example: Pulling names out of a hat Cluster – Divide the population into groups, randomly select SOME of the groups and collect data from selected groups. Example: Exit Polls

Methods of Sampling Systematic – Select a random starting point, then choose every nth subject. (not used much) Stratified – Divide the population into at least 2 group, and then pick SOME from each group. (used most often) Example: high school -> grade level

Types of Experiments Observations – Watches what happens/happened at draw conclusions. Note: NO interaction or modification. Examples: Surveys Experiments – Researcher manipulates one variable and tries to determine how the manipulation influences the other variables. Note: There IS interaction and modification Example: Clinical trials