Week 5 Lecture

# Week 5 Lecture - Week 5 Estimating and Sample Size The Big...

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Week 5: Estimating and Sample Size The Big Picture Sometimes when we get this far into a course it is difficult to see the forest from the trees. I'd like to have you step back so I can share a larger perspective of the material we are learning this week. This course began by exploring “statistical thinking,” for example, how to calculate the probability that three out of four children born to a couple are girls. As we get more into the material for this class, we increasingly focus on how statistics are used in a research context and for making decisions. Last week we delved into the normal distribution curve or the bell curve. This week we will build on that foundation by examining estimation, and next week we'll learn about hypothesis testing. Statistics can be differentiated into descriptive and inferential statistics. Descriptive statistics examines central measures (ie mean) and measures of variation or spread (ie standard deviation). These measures are used to describe a sample, and thus the name “descriptive” statistics. Inferential statistics use the measures we explored descriptively and infers how the sample may generalize to the population. It is important to remember that we are always interested in the population, but because we are not able to fully measure the population, we take the results gleaned from samples and infer these results to the population using statistical tests. We select samples from the population we are interested in and use the information to generalize to the population. We generalize to the population using two different methods: estimation and hypothesis testing. I want you to think about having two boxes on a shelf. One of the boxes is labeled “descriptive statistics,” and it contains all those measures we have grown to know and love such as mean, mode, median, range, variance, and standard deviation. The second box is labeled “inferential statistics.” Now imagine that inside the inferential box there are smaller boxes, and one is labeled “estimation” and the other “hypotheses testing.” Whenever we work with estimation or hypothesis testing, remember that these are both inferential statistical methods. In estimation, we

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## This note was uploaded on 12/04/2011 for the course FLASH 101 taught by Professor Mrburns during the Fall '11 term at Baker MI.

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Week 5 Lecture - Week 5 Estimating and Sample Size The Big...

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