COMPUTER ASSIGNMENTS No 6
For this computer assignment, I decided to use JavaScript Estimations with Confidence link. I
used this computer calculating method on homework assignment Example 8.6 (99% Confidence
Interval). I already completed Example 13 and have the answers, so this assignment is basically
to see how accurate this calculator is compared to the text book answers and does it save time
over the “calculating by hand” method. Example 8.6 gave me 50 observations (n = 50) and their
data. It also said to estimate the mean, µ using a 99% confidence interval. The only data that
needed to be entered for this JavaScript calculator was the values of each of the n = 50 samples
and the confidence level (.99). So after I entered the required data samples from Example 8.6 I
simply hit calculate and was given the estimated mean with lower and upper limits, estimated
variance with lower and upper limit, and the estimated standard deviation with lower and upper
limits. Example 8.6 said to find the mean 99% confidence interval, It can be found on the chart
below under the estimated means lower and upper limit which is (1.177, 1.454). The confidence
interval from the text book was (1.181, 1.449). They are pretty close but the lower limit is .004
off and the upper limit is .005 off. I double checked to see if everything was entered correctly
and it was. The values of the mean and standard deviation were the same as in the text book.
The only reason I could find for this small error is that we did some rounding in Example 8.6 that
could have put the ending values a little off. Remember these calculations are for
ESTIMATING so something being only .004 off is ok in estimating. In fact if the text book was
estimating and we were estimating it makes sense that they would be a little different. In the
future, I would however, like to find out why this JavaScript calculator came up with a different
confidence interval than the book did. If the JavaScript’s calculations are accurate enough to be
accepted and useful, then I would definitely use it again in the future. It does cut down on a lot
of time, other than entering all of the sample data. But with only entering the sample data,
confidence level, and clicking enter, you get the estimated mean, confidence interval (lower and
upper limits of the mean), estimated variance with lower and upper limit, and the estimated
standard deviation with lower and upper limits. This JavaScript calculator could be very useful
in a problem where the mean, variance, standard deviation, and all of their lower and upper
values needed to be found.
SEE CALCULATION TABLE ON NEXT PAGE
How to Test for Randomness
I also reviewed the page on how to test for randomness. You simply entered all of your data and
clicked on the calculate button and it gave you the p-value, Number of Runs (R), and a
conclusion which told you something like, “Little or no real evidences against randomness”. It
was a very simple chart, but I think there should have been a little more explanation on how it
got to its conclusion. I researched it for a while and still couldn’t come up with an answer. I
guess I’ll have to come back on this one.