MAT 214 Lab 1: Introductionand Descriptive Statistics Fall 2016
When writing your lab reports, all graphs and data must be included. This should be done by copying and pasting the graphs and statistics from Minitab into Word. Discuss and summarize all your answers to the questions in the lab, as well as anything you find particularly interesting, surprising, or confusing in the lab.
Refer to the lab report template and examples of a good and poor lab reports online.
In the following → means Click on and→→means Double click
I. Getting started with Minitab
- Opening Minitab→→ Educational Software→→Minitab.
- Finding the data set: →File→ Open Worksheet→→ Look in Minitab Sample Data folder →→ Pulse.mtw → Ok
To find the description of any of the data sets from Minitab: → Help →Data sets →→ the data you are working with.
- Open a blank document in Microsoft Word. You will be using the Word document to write your lab report. As you complete each of the following steps, copy and paste the graphs and the appropriate sections of the session window into your Word document. To copy a graph to Word, position your mouse cursor on the graph, right click your mouse, click Copy Graph, bring up your Word document, right click your mouse and select Paste. This will allow you to write your lab report and have the graphs integrated into your report, making it easy to follow and understand. Prior to copying a graph to Word, you need to put your name in the graph window. To do this, right click in the graph window, →add →subtitle or footnote, type your name in the window, → OK.
*Important: When saving your work from Microsoft Word be sure to save to your P: drive.
II. Starting the lab
Compute descriptive statistics for Height and Weight:
→Stat→Basic Statistics→Display Descriptive Statistics→→Height and Weight→ OK
What is the mean (average) height and weight of the Statistics Students?
Compute Frequency Tables for Height and Weight:
→Stat→Tables→Tally Individual Variables→→Height and Weight→ OK
What are the most frequent heights and weights of the students?
How many students have these heights and weights?
Display Histograms for Height and Weight:
→Graph→Histogram→→Simple graph→→Height and Weight→OK
By looking at the histogram what can be said about the heights and weights of the students? Does this agree with the results you found from the frequency tables? How meaningful do you think these results are? Why? Describe the shape of the histograms: are there any possible outliers? Does histogram look uniform, symmetric?
Display a plot of Weight vs. Height
→Graph→Scatterplot→→Simple graph→→Weight and Height→ OK
What can you say about the plot of the height vs. weight? What does the trendseem to be?
Make sure you use appropriate X and Y axis.
Display a pie chart for Sex
→Graph→Pie Chart→ the box Categorical Variable→→Sex→OK
Note that 1 represents males and 2 represents females.
What percent are males? Females?
III.Part II showed you how to use several Minitab features. However, the statistics produced probably aren’t as useful as they could be. Gender should be taken into account. Now we will separate the data into two classes and then repeat part II for females and males. First, we want to change the names of some columns so we can readily identify what is stored in a particular column.
Change name C9 to FHeight, C10 to FWeight, C11 to MHeight, and C12 to MWeight by typing these names in the gray box below C9, C10, C11, and C12 respectively.
To extract the Female Height and Weight Data and put it in FHeight and FWeight:
→Data→Copy→ Columns to Columns→in the box Copy From Columns→→Height and Weight→the drop down menu beside the window containing “In new worksheet”and select “In current worksheet, in columns”→the box directly below the drop down menu
→→FHeight and FWeight:uncheck Name the columns containing copied data
→Subset the data→ radio button beside Rows that match→condition
→box to the right→→Sex→→ “=”box below and click “2”→ OK→OK→OK
NOTE: Sex = 2 will be displayed in the condition box.
Repeat the previous instructions to extract the data for males using “1” as the code rather than “2” and MHeight and MWeight in place of FHeight and FWeight.
Repeat part II with the Female Data and Male Data and comment on the differences in the graphical summaries.
Compare the ranges of histograms from part II and histograms of data separated by sex.
You could graph several histograms on one graph by changing the options in Multiple graphs (In separate panels of the same graph)
Would the percentage of males and females help to explain why the histograms of weight and height look the way they do? Why?
What is the mean height and weight for the females? Males? Support your answer by Minitab.
What are the most frequent height and weight of the females? Males?
Do these results seem to be more meaningful now that gender is taken into account?
Why? Are there any other factors that should be taken into account to make the results more meaningful?
To display a plot of Weight vs. Height
→Graph →Scatterplot →→with groups→→Weight and Height → categorical variables →sex→OK
Make sure you use appropriate X and Y axis.
- Does the same trend hold for the plot of height vs. weight for females/males as it did for all students?
Construct a Box Plot for Heights
→Graph→Boxplot→→Simple→→Height→OK
Repeat for Weight
Construct a BoxPlot for Female Heights and Male Heights
→Graph→Boxplot→→Simple→→Height→Multiple Graphs→By Variables
→ in top window labeled “By variable” enter “sex” into “with groups in separate panels
→ OK→OK
Repeat the above toConstruct a Box Plot for Female Weights and Male Weights.
We will discuss boxplots in detail in class shortly, but for now here are a few things about them that you need to know. The gray area represents the middle 50% of the data set and the thin lines are representing the outer 50%. There is a line in the middle of the gray area that represents the value of the median, which in this case is close to the mean (average), of the data.
What conclusions can be drawn by looking at these boxplots?
Compare the boxplots of weights and heights by themselves with the boxplots of weights and heights when gender is taken into account.
Does boxplot analysis support or contradict your histogram conclusions above?