Introduction to Statistics 2
trvghtstarserviges
wk1-hw1_part_2.docxWEEK 1, HOMEWORK 1- PART 2: LANE C 1-2,; ILLOWSKY C 2 SECTIONS 2.1 – 2.4
HW1 – Part 1 dealt with what data are and how to collect valid random data. We also talked about how data “samples” are intended to give us an idea of an entire population. Of course sample size affects everything.
We now continue with DESCRIPTIVE STATISTICS concepts, such as DISPLAYING our data in the hopes of seeing some pattern as distinctly as possible. So, who cares if there is a pattern? Well, if we see a bell curve shape we likely have a NORMAL distribution and all our statistical analyses will work (give us valid results).
BUT, always remember that statistics proves NOTHING by itself. The calculated numbers simply give us support for our hypothesis (our ideas). Remember too that as with stock prices, past data do NOT predict future performance. Of course all statistics mean NOTHING IF the data are not true random samples that reflect the entire population of concern.
OPEN THE EXCEL TABLE PROVIDED WITH THIS HOMEWORK AND ANSWER THE FOLLOWING FIVE (5) QUESTIONS
#7. Draw a PIE CHART showing the total ANNUAL cost split among these three EXPENSE categories: gas, food, electricity (a hand drawing is fine). EXPLAIN HOW EXCEL OR YOU DETERMINED THE ANGLES OF THE 3 WEDGES IN THE PIE CHART (DUST OFF GEOMETRY AND TRIG)
#8. Draw a STEM & LEAF diagram of the MONTHLY INCOME numbers. Explain how you would handle this if the expenses had more significant digits (e.g., $3189 instead of $3200, etc.). This is a possible shortcoming of displaying data in a stem & leaf diagram)
#9. HAND DRAW a DOT PLOT for any one data column. (Few seem to get this one right) Look at the LANE text example. Try putting the $-amounts along the bottom axis and a dot for each time a value occurs above that number. You can do this sideways too (see Lane).
#10. SUMMARIZE (in your own words AFTER READING THE TEXTS) what each of the data displays (i.e., pie chart, bar graph, stem & leaf, and dot plot) above is BEST suited for and what, if any, are its LIMITATIONS. Which display do you feel gave you the best “picture” of the shape of the data distribution and/or the most information about it?
