Stanislaw Posted January 25, 2012 Report Share Posted January 25, 2012 *sigh* just finished mine.I like math IAs but I get frustrated quite easily when I'm stuck...Especially the logistic regression. I couldn't find any computer software to do it so I spent a few hours on K/L/M alone.. Reply Link to post Share on other sites More sharing options...
mavv Posted January 26, 2012 Report Share Posted January 26, 2012 *sigh* just finished mine.I like math IAs but I get frustrated quite easily when I'm stuck...Especially the logistic regression. I couldn't find any computer software to do it so I spent a few hours on K/L/M alone..Your GDC will produce a logistic regression, see earlier posts. Well done for finishing though Reply Link to post Share on other sites More sharing options...
f.talero Posted January 29, 2012 Report Share Posted January 29, 2012 I was told to apply the logarithmic function to my model through the list option on the calculator where I get numbers for a, b, and c...what do those mean?: Reply Link to post Share on other sites More sharing options...
Scootaloo Posted January 30, 2012 Report Share Posted January 30, 2012 I used the sextic function that was recommended by Desy and I found a model that fits 8/10 of the points that were given. Should I revise my model, or would that be fine? Reply Link to post Share on other sites More sharing options...
mumu13 Posted January 30, 2012 Report Share Posted January 30, 2012 If any one needs help with this task, I finished it last term, so just ask Got 19/20 points on it. hey can you help me with the task at hand. what is the trend line for the original data? Reply Link to post Share on other sites More sharing options...
mavv Posted January 31, 2012 Report Share Posted January 31, 2012 I was told to apply the logarithmic function to my model through the list option on the calculator where I get numbers for a, b, and c...what do those mean?: Are you sure it was logarithmic and not logistic, a,b, and c are the parameters. Reply Link to post Share on other sites More sharing options...
holly Posted February 2, 2012 Report Share Posted February 2, 2012 (edited) I was told to apply the logarithmic function to my model through the list option on the calculator where I get numbers for a, b, and c...what do those mean?:The formula given to you on your calculator should look very similar to the researcher's model except with different variables (a, b, c instead of k, l, m). Edited February 2, 2012 by holly Reply Link to post Share on other sites More sharing options...
Anmol929 Posted February 6, 2012 Report Share Posted February 6, 2012 Can i get some help too please? Mines is due on thursday and I'm completely lost. How do you find a model? If any one needs help with this task, I finished it last term, so just ask Got 19/20 points on it, so thats AWESOME Please i would really appreciate some/much help!!! dunno what its all about... at the moment i don't know where to start! any hints??? thanks Reply Link to post Share on other sites More sharing options...
holly Posted February 7, 2012 Report Share Posted February 7, 2012 (edited) Can i get some help too please? Mines is due on thursday and I'm completely lost. How do you find a model?It's not as difficult as it seems. First plot the points and see what "shape" it makes from the data the paper gives you. Let's say it looks like a parabola. Then your model might be a quadratic function (y = ax2+bx+c). Then plug in the x and y values you know (which is the first table they gave you) and find the missing variables (which in this case is a, b, and c) by using substitution. I actually used a very simple function to find my model so it's not as hard as you think. Good luck!I hope this makes sense... I can explain more if you need. Edited February 7, 2012 by holly Reply Link to post Share on other sites More sharing options...
nabsak1 Posted February 9, 2012 Report Share Posted February 9, 2012 How would you revise a model? I got my cubic function but on the GDC, it only hits five of the ten points. I don't want to use the sixth polynomial thing on excel b/c I have no idea how to explain it. Any suggestions? Reply Link to post Share on other sites More sharing options...
nabsak1 Posted February 9, 2012 Report Share Posted February 9, 2012 basically, I was able to use matrices in order to find my equation. But how can I play around w/ that equation? I dont' really know how to do any of the analysis stuff, I basically just know how to find my models... Reply Link to post Share on other sites More sharing options...
Guest Juicebox Posted February 9, 2012 Report Share Posted February 9, 2012 basically, I was able to use matrices in order to find my equation. But how can I play around w/ that equation? I dont' really know how to do any of the analysis stuff, I basically just know how to find my models...I used matrices to find a cubic equation but the GDC always says ERR:SINGULAR MAT has this happened to u? Reply Link to post Share on other sites More sharing options...
Guest Juicebox Posted February 9, 2012 Report Share Posted February 9, 2012 on the GDC when i select stat -> CALC -> Logistic I get values for a b and c how do I know which one is K L or M? Reply Link to post Share on other sites More sharing options...
amg Posted February 10, 2012 Report Share Posted February 10, 2012 If any one needs help with this task, I finished it last term, so just ask Got 19/20 points on it, so thats AWESOME I could use some help as well, what function did u use, i was thinking of using wither an exponential (so that the graph never goes below zero) or the cubic (cause if fits great with the points), but i have no friken idea how to find a,b,c,d (in a ax^3 + bx^2 + cx + d) or a,b (for ae^bx) analitically... any idea?? Anyway I could see your portfolio task? Reply Link to post Share on other sites More sharing options...
Stanislaw Posted February 10, 2012 Report Share Posted February 10, 2012 (edited) Anyway I could see your portfolio task? No, we won't do the task for you. on the GDC when i select stat -> CALC -> Logistic I get values for a b and c how do I know which one is K L or M? You can guess Or you can simply replace K,L and M by A,B,C and see when they accurately represent the data you were given. In my IA, before going in to ABC, I analyzed and specified how the equation would react when the values of K/L/M increased/decreased, that way it gave me [more importantly, the reader] a better understanding of the Verhulst model. basically, I was able to use matrices in order to find my equation. But how can I play around w/ that equation? I dont' really know how to do any of the analysis stuff, I basically just know how to find my models... Your equations will most likely contain Y's, X's and constants. Try altering the constant values[coefficients] in front of the variables. If its a linear model [y = mx + b] then just play around with M and B and see how the equation is altered. How would you revise a model? I got my cubic function but on the GDC, it only hits five of the ten points. I don't want to use the sixth polynomial thing on excel b/c I have no idea how to explain it. Any suggestions? The sixth polynomial's "formula" isn't anymore complicated than a quadratic formula. When you say it "hits", how close are we talking? I mapped 6 different functions through Excel, and they all had a coefficient of determination of >0.95 What you have to keep in mind, is your trendline's "behaviour" over a longer period of time. Does it accurately represent China's past and future demographics? I got 18/20 on my most recent math IA, I'm quite happy. If you have any specific questions, feel free to post. But asking for an IA, or the model that fits best, is not available. Most important lesson learned was: correlation does not imply causation. Edited February 10, 2012 by Stanislaw 1 Reply Link to post Share on other sites More sharing options...
Guest Juicebox Posted February 11, 2012 Report Share Posted February 11, 2012 when it says define all relevant variables and parameters I don't know what they mean by parameters? Reply Link to post Share on other sites More sharing options...
nabsak1 Posted February 12, 2012 Report Share Posted February 12, 2012 Basically it means the limiting factors. Like can your x value be a negative number? Stuff like that.@Stanislaw: Meaning that it touches the points. Basically when I graph the points with my line, six of the points are colored in on the GDC. And I tried finding the sixth polynomial function using matrices but I got a weird graph, like a tangent function. I don't know what I'm doing wrong b/c I doing the same thing I do with finding my cubic function: I use matrices for both, except all I'm doing is I'm adding more rows and columns. I used excel in order to plot the function, and it was perfect for the population from 1950 to 1995, so could i just use that? I don't know how to show mathematical process for it becuase I just put it in on excel and it wasn't working when I used matrices. So I'm not sure what to do. The logistic function is best when thinking about China's past and future demographics. But since the IA says that were supposed to investigate diferent model functinos that best model the population from 1950 to 1995, I'm thinking we're only supposed to focus on what we're given rather than overall Reply Link to post Share on other sites More sharing options...
Janus Antonio Agbing Posted February 12, 2012 Report Share Posted February 12, 2012 idk if this is against the rules or not so inform me if it is, but when i use sinreg on the data using a ti 84, it spits out sin(6.2x+3.1)+875, and when i graph it, it's just a line and not a sinusoidal. (the numbers are much longer than that but you get the point) but when i use graphmatica, it spits out a different set of numbers and it actually forms a sinusoidal. Reply Link to post Share on other sites More sharing options...
nabsak1 Posted February 12, 2012 Report Share Posted February 12, 2012 idk if this is against the rules or not so inform me if it is, but when i use sinreg on the data using a ti 84, it spits out sin(6.2x+3.1)+875, and when i graph it, it's just a line and not a sinusoidal. (the numbers are much longer than that but you get the point) but when i use graphmatica, it spits out a different set of numbers and it actually forms a sinusoidal.I didn't use sin regression, I would suggest either using cubic, quartic (they end up being almost the same) or a sixth polynomial function. You can do all of this on Excel.I have a question: for teh last part of the IA, when it asks us to plot the line along with the new points, I plotted it, and nothing is showing up on my graph. Just my points are coming up but the line is no one to be seen. WOuld anyone mind helping/explaining this? And this is for both my sixth polynomial function adn my logistic function Reply Link to post Share on other sites More sharing options...
Nicktom24 Posted February 12, 2012 Report Share Posted February 12, 2012 I am really confused (I've seen this a lot today haha) but how on Earth do you take a screenshot of a graph made on a graphing calculator? Reply Link to post Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.