Download Exploratory Stats 89 how to

TI89 Calculator Name:____________________________________________ Section 1 – Data Entry, Data Manipulation and Summary Statistics For the following problems we have a list of exam data from a professor in the statistics department. In giving this exam, the professor found that the exam was too difficult and the scores were lower than she intended. She decided that she wanted to transform the data to change the spread of the data and have a larger average score. In this section you will learn to enter data, manipulate data and find the one variable summary statistics. Original Exam scores: 42.75 53.25 51 53.25 36.75 54 43.5 33 47.25 51.75 60.75 54.75 39.75 54.75
The first thing you need to do is enter the data into your calculator to do this, do the following instructions. On your main screen go to the data matrix editor. Open a new data set. Type = data, folder = main. Name your variable exam and press enter. Enter the 14 data points into c1. Next you need to transform the data to the professor’s specifications. She wants each data point to be multiplied by 4/3 and then 15 points should be added to that. To do this in your calculator, do the following instructions. Scroll up until you get to the column header c1. Press right to c2 and press enter. Type in the following equation: 4/3*c1+15 and press enter. This should give you a new list of numbers in c2 that correspond to the transformed data. Give the transformed list of numbers here: Next we will find the summary statistics of this transformed data. The professor is interested in finding the mean, median and sample standard deviation. To do this, in your calculator, do the following instructions. Press F5 (for calc). We are looking to do OneVar statistics. The x variable is c2 and use the default “no” for freq and categories. is the sample mean, medStat is the median and Sx is the sample standard deviation. What are these three values? Mean = Median = Sample Standard Deviation = TI89 Calculator The summary statistics also give σx. This is notation for standard deviation as well. The calculator finds σx with the equation , while it finds Sx with the equation . Which one were you taught is the proper way to find the sample standard deviation? Use this when answering the above question. Section 2 – Saving data and more on Summary Statistics‐Widget Problem For this section we will be working with a data set from the book. If you do not have the book, please make sure you get a hold of this data set. It can be found in section 5.3, table 5.1. This data will be used throughout the semester, so please do not delete this data set. Create a new data set and call it widget. In columns c1 through c6 type in the data from the table. Using what you learned in the last section, find the following summary statistics for each data set. Note that you can check to make sure you’ve inputted the data properly by checking to see that your mean, median and standard deviation match the values given in the book. Set 1 Set 2 Set 3 Set 4 Set 5 Set 6 Mean Sample Size Sum of Obs. Low Q1 Median Q3 High Sx σx If you quit out of your data set, you can always reopen it (which you will need to do throughout the semester). To do this, on you main screen, go to data/matrix editor. “Open” variable ‐> widget. Note that any data sets that you have created should be stored here as well. TI89 Calculator Section 3 –Graphs, Reopening Data Sets and Clearing Data Sets In this section, we will revisit a data set that we have already used, create some graphs with that data set, and then clear the data set from memory. BoxPlot: To start press the green button then F1 (Y=). In this screen you can scroll up to find “Plot 1”. Press Enter on Plot 1. We wish to create a box plot. Our x variable is c2 (our transformed data) and keep the default “No” for freq and categories. Now press the green button then F3 (for graph). You may need to do a ZoomData if the boxplot does not show up fully on your screen. To do this type F2 9ZoomData. You can find the 5 number summary from this box plot by tracing (F3) the boxplot. Sketch the boxplot, labeling appropriate markers on the plot with their values. Histogram: To create a histogram of the data again press the green button and F1 (Y=) and scroll up to “Plot1” and press enter. Change the graph type to histogram. Our x variable is still c2 and you will have to find a suitable bucket width to fit the data. (Hint: Don’t use a bucket width of 1). ZoomData will not work to help place the data properly on the screen. You will have to change the window manually. To do this press the green button then F2 (for window). Then you will have to think logically about what the x and y axes represent to find a window that will fit your histogram. What does the y‐axis represent in the histogram? For the given bucket widths that you’ve chosen, how small and how large will y need to be? What does the x‐axis represent in the histogram? For the given data, how small and how large will x need to be? Sketch the histogram, appropriately labeling the axes. TI89 Calculator Give some characteristics that define the distribution of the histogram (symmetric, bimodal, skewness, outliers, etc.) We are now done with the exam data. To get rid of a variable that you no longer need, start off in your home screen. Click the catalog button and scroll to DelVar, then type in “exam” (or whatever you called the exam data set). Press Enter and your calculator should report “done”. The exam data variable has now been deleted from your calculator’s memory.