Lesson 0: Overview

Lesson 0: Overview

Why study statistics?

To start this course off, a good question to ask might be, "Why Study Statistics?" The American Statistical Association has considered this same question and presents their answer if the form of video interviews of a variety of statisticians. Enjoy!

Why You Need to Study Statistics

Why Study Statistics?

  1. To evaluate printed numerical facts.
  2. To interpret the results of sampling or to perform statistical analysis in your work
  3. To make inferences about the population using information collected from the sample

What Do Statisticians Do?

  1. Gather data
  2. Summarize data
  3. Analyze data
  4. Draw conclusions and report the results of their analysis

0.1 - What is Statistics?

0.1 - What is Statistics?

Statistics

The art and science of answering questions and exploring ideas through the processes of gathering data, describing data, and making generalizations about a population on the basis of a smaller sample.

Statistical literacy

“People’s ability to interpret and critically evaluate statistical information and data-based arguments appearing in diverse media channels, and their ability to discuss their opinions regarding such statistical information”

Statistical literacy is important because you are faced with statistics problems in your personal and professional lives.

Examples

Choosing a Medication

Your doctor gives you the option to choose one of two different medications. She provides you with research studies comparing the two medications. How can you use those research studies to inform your decision?

Fantasy Football

In planning for your fantasy football team you come across many tables of statistics. How can you synthesize all of those numbers to best inform your fantasy football draft?

School Curriculum

Your child's school is selecting a new science curriculum. The administration has narrowed it down to three different curricula and is asking parents to vote. What information would you ask for to inform your vote?

Driving to Work

There are two routes that you could take to get to work in the morning. If you go through town, it usually takes between 6 and 14 minutes, depending on the traffic and red lights. If you take the interstate, it consistently takes 10 minutes. Which route will you take to work this morning?

Marketing Decisions

Your company has put you in charge of making a decision between two marketing campaigns. How can you design a research study to collect data to inform your decision?


0.2 - Foundations

0.2 - Foundations

Populations and Parameters

Population
any large collection of objects or individuals, such as Americans, students, or trees about which information is desired
Parameter
any summary number, like an average or percentage, that describes the entire population

The population mean $\mu$ (the Greek letter "mu") and the population proportion $p$ are two different population parameters. For example:

  • We might be interested in learning about the average weight of all middle-aged female Americans. The population consists of all middle-aged female Americans, and the parameter is $\mu$.
  • Or, we might be interested in learning about the proportion of likely American voters approving of the president's job performance. The population comprises all likely American voters, and the parameter is $p$.

The problem is that almost all of the time, we don't — or can't — know the real value of a population parameter. The best we can do is estimate the parameter! This is where samples and statistics come in to play.

Samples and Statistics

Sample
is a representative group drawn from the population
Statistic
any summary number, like an average or percentage, that describes the sample

The sample mean, $\bar{X}$, and the sample proportion, $\hat{p}$, are two different sample statistics. For example:

  • We might use $\bar{x}$, the average weight of a random sample of 100 middle-aged female Americans, to estimate $\mu$, the average weight of all middle-aged female Americans.
  • Or, we might use $\hat{p}$, the proportion in a random sample of 1000 likely American voters who approve of the president's job performance, to estimate $p$, the proportion of all likely American voters who approve of the president's job performance.

Because samples are manageable in size, we can determine the actual value of any statistic. We use the known value of the sample statistic to learn about the unknown value of the population parameter.

Techniques of describing data in ways to capture the essence of the information in the data are called descriptive statistics. For example, the sample mean is a descriptive statistic. To draw conclusions from data about the population is called inferential statistics. Here is a picture that demonstrates inferential statistics.

Samples taken from a population are used to make an inference about the entire population.


0.3 - Introduction to Minitab

0.3 - Introduction to Minitab

Minitab®

The Minitab program is required as part of this course. Install the software and enjoy this versatile statistical software which includes clear help explanations and easy-to-understand printouts.

To begin Minitab, double-click on the Minitab icon on your desktop or select Minitab from the program folder.


Interface

As is typical in most software programs, the menus are found at the top of the application window. With the Minitab application two windows are also opened by default: the session window and a worksheet. The active window has a blue title bar and other windows have a gray title bars. If you want one of the other windows to be the active window, just click on it.

  • Session Window: The session window displays non-graphical outputs such as tables of statistics and character graphs. (If the Session window is not open, select Session from the Window menu to open the window.) You can edit the Session window.
  • Worksheet Window: This is the window where we enter, name, view, and edit data. The data for each variable is stored in a different column. At the top of each column is a blank cell for specifying the name of the variable. You can simply click on a cell at the top and enter the name.

Entering Data

Note! Users accessing Minitab via Penn State's RemoteApps or WebApps will not be able to use this copy and paste technique. Instead all files must be uploaded into your PASS space and open these files in Minitab from this location in PASS. See WebApps on the STAT Online site for more information.)
  • Entering Data (entering manually): Activate a Worksheet window by clicking once in it. Click the cell where you want to enter the data and type it in. Use [Enter], the mouse, or arrow keys to move to different cells. If an observation is entered incorrectly, simply make that cell active again and type in the correct value.
  • Entering Data (importing from a file): There are basic ways to enter data into the Minitab worksheet. Here are two of the most common...
    • Copy and Paste: Choose File > Open Worksheet. For example, if you want to add data values from a data file or from an Excel spreadsheet, one simple way to do this is to open that file, highlight the portion you want to add, then select Copy from the Edit menu. Go back to Minitab, activate the cell you want to paste the data into, then select Paste from the Edit menu.
    • Import Files: Select the Open Worksheet option in the File menu in Minitab. Select the type of file that you are looking to import, (this could be a Minitab file, text file, Excel file, etc.). Locate and then import this file into the Minitab worksheet.

Minitab Resources


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