MAT 240 Journal Aid Transcript Video | Assignment
Added on - 18 Sep 2019
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MAT 240 Module 7 Journal Aid TranscriptThis video is an aid for the journal assignment in week 7 of MAT240.In weeks 6 and 7, we’ve been looking at regression analysis. They topic of this journal in week 7 is ...regression analysis. We will be looking at 2 different problems:One of them relates low temps in July and August. We’re interested in knowing “do hot Augusts followhot Julys... do cool Augusts follow cool Julys”, in other words is there a correlation between the temps inJuly and August. Before doing the analysis, I would say “I don’t know”.Then, the second regression is to compare the precipitation or rainfall in July and August. The samequestion “do rainy Augusts follow rainy Julys and dry Augusts follow dry Julys”? Here again I’m not sure.I’m not a meteorologist.[1:50] For our first regression, we’ve been looking at the variable MMNT, the mean minimumtemperature. For this analysis, I’ve chosen just the July and August temperatures. We want to knowwhether they are correlated. In other words, do hot Augusts follow hot Julys. Or maybe, do cool Augustsfollow hot Julys. So we want to do a regression model. Since August is the later month in time, it makessense to have August as our Y variable and July as our X variable. We’re not too good at time travel, sopredicting forwards is the way to go.We have a linear modelMin_Aug = slope times Min_July + intercept[3:15] We want to test whether the slope is 0 or different from 0. Rejecting the null means a correlation.Not rejecting the null means insufficient evidence to show a correlation.So what do we do? We go to StatCrunch. You should be very familiar by now. I’ve already logged in ... Iopen StatCrunch and I get a blank dataset. We load from Shared Datasets and, as usual, searching forsnhu mat240 ... and we see Central Park and the Journal. Of course, I’m going to do Central Park again –you need to do your Journal.[4:45] Here is the data. The new variables are all the way to the right. In 1876, it was 22.2 degreesCelsius as the mean minimum in July and 20.1 Celsius as the mean minimum in August.We can jump right into regression because the regression output will give us some information to assessthe quality of this model. Stat – Regression – Simple Linear. Simple means one X variable. We’re usingJuly’s minimum to predict August’s minimum. Compute ... and there are two screens.[6:10] The first screen is numeric. You can see that the p-value for the slope is less than .0001 – thatmeans an extremely strong correlation. The slope is positive – that means an extremely strong positivecorrelation. So what the data show, at least for Central Park New York, is that July and Augusttemperatures are positively correlated. That means hot Augusts follow hot Julys in general, and coolAugusts follow cool Julys, in general.