Chapter 4 part 1

# Chapter 4 part 1 - Chapter 4: Probability Chapter 4:...

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Chapter 4: Probability

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Chapter 4: Probability language of uncertainty: the proportion of outcomes the fraction of times the risk of something the chance of an event the likelihood of some occurrence
Probability uses population info to make predictions about samples Example: Probability is when we know something about the population and then from there we can make predictions about what will happen in the sample Probability Population is 15% red flowers and 85% yellow flowers Population What is probability that: You sample 3 flowers and get all red ones? sample

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Varies from Statistics Statistics uses sample information to make inference to what is occurring in the population Statistics is when we take a sample and then draw inferences to the population; so in this case, we don’t know about the population I collect a sample of 3 red flowers Sample I infer the entire population is red Population Inference
Because probability is often called the ‘vehicle’ of statistics, we are going to focus on probability for several weeks Note the word ‘probability’ is common in language And not always used in a statistical sense

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Probability Example M&Ms are supposed to be 10% blue , 10% brown , 10% orange , 10% green , 20% red , 20% yellow , and 20% purple .— this is what the population is supposed to be You can use this population information to make a guess at the number of each color of M&Ms you would expect in a bag (sample)
Example If a bag contains 100 M&Ms then you would expect 10 blue , 10 brown , 10 orange , 10 green , 20 red , 20 yellow , and 20 purple . Will you get exactly these numbers? Probably not – but this would be your best guess of what to expect in a sample given these population proportions

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Definitions: spinner with 4 colors E Definition Example An experiment: process that yields 1 result or observation In the problem above, the experiment is spinning the spinner outcomes : all the possible results The possible outcomes are landing on yellow, blue, green or red An event is one outcome of interest We might be interested in landing on blue Probability is the measure of how likely an event is The probability of landing on blue is 1 out of 4 =1/4 th
Your turn You keep track of the sex of each person going into the Student Union. You want to know the percent of women students that enter each day. What is the: Outcomes: either male or female Event: women entering Probability of this event: depends on # of women on campus

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3 ways to to find the probability of an event occurring Empirically, Theoretically, Subjectively
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## This document was uploaded on 11/04/2011 for the course BIOM 301 at Maryland.

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Chapter 4 part 1 - Chapter 4: Probability Chapter 4:...

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