Is this an exponential function

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The SARS virus apparently was based on an exponential function is this true?

Upon examining the following table, I would say yes but one of my colleagues reckon that it's not and he has supporting evidence. However, the table below once sketched does have an exponential function beginning from coordinate (0,0)

Can someone help me to find out the right interpretation?

SARS virus

week(x) 1,2,3, 4,5,6,7
# of cases (y) 6,44,139,318,601,1014,1576

Why was the disease not spread exponentially according to the data above?

thank you in advanced
 
You can simply plot your values using something basic like Microsoft excel. And adding a trendline, are you getting your log's and exponential function's mixed up??

Send me a PM if your unsure, It is quite straight forward..
 
PM=Private Message.


Does your calculator do power regressions?.

I ran your data through my TI-92 and arrived at a regression formula which matches very closely.

Let kidfromoz show you the Excel thing. It's very nice.
 
For what it's worth, quadratic regression gives a pretty good match for x> 1.

Steve
 
I have done the excel thing

but I am sure that it resembles an exponential curve...
 
Can you make out the equation on the chart?.

It's \(\displaystyle \L\\6.0155x^{2.8615}\)

Note the R^2. The closer that is to 1, the better the approximation.

Insert your x values(1,2,3,etc). See what you get.


sars9eb.jpg
 
Galactus I got that...

but doesn't that resemble an exponential function? The question says, prove my mathematical modelling that it's not an exponential function...
 
It may resemble, but it's not.

Here's an exponential function. Note the equation in terms of e.

The first one(the best one) is a power regression. Note the power of x.

The R^2 in this one is not as close as the power regression model.

sarsiimedium9fr.jpg
 
americo74 said:
The question says, prove my mathematical modelling that it's not an exponential function...
Click to expand...
Ah. You hadn't mentioned that in your original message.

It's almost always best to include the entire question in your initial posting.

Thank you.

Eliz.
 
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