HP50G Trend Lines: Solve Absorbance vs. Concentrations Easily

[Whalstib]

Hi,

I'm taking 3rd semester chemistry and we often have to take a series of for instance:
Absorbance vs. concentrations data.

Usually a series 5 experiments with the goal to have a spread sheet type answer. I use Excel or what ever I have handy just to find the y=mx + b value for "m".

I want to use my HP50G to accomplish this while in class.

I looked in the HP50G manual and there does appear to be a way to create trend lines but is not working for me. The examples are a bit more involved in the answers.

I have a feeling I'm doing something wrong in the chose of which menu to use... I know my inputs are correct and formatted correctly so either this isn't possible or as I said I'm starting out on the wrong foot.

here's what I've been doing according to the manual:

Stats > Fit data > Linear Fit
I enter the data in A column=x axis, B column=Y axis

Answers not in the format I need.
None of the other choses seem to get me there either..

is there a simple way to do what I'm attempting so I have this with me always?

thanks,

Whalstib

 

[Whalstib]

Actually All I'm after is a way to use a linear regression on a series of data points Y vs. X.

Any advise welcome.

Whalstib

 

[rs1n]

Hi,

I'm taking 3rd semester chemistry and we often have to take a series of for instance:
Absorbance vs. concentrations data.

Usually a series 5 experiments with the goal to have a spread sheet type answer. I use Excel or what ever I have handy just to find the y=mx + b value for "m".

I want to use my HP50G to accomplish this while in class.

I looked in the HP50G manual and there does appear to be a way to create trend lines but is not working for me. The examples are a bit more involved in the answers.

I have a feeling I'm doing something wrong in the chose of which menu to use... I know my inputs are correct and formatted correctly so either this isn't possible or as I said I'm starting out on the wrong foot.

here's what I've been doing according to the manual:

Stats > Fit data > Linear Fit
I enter the data in A column=x axis, B column=Y axis

Answers not in the format I need.
None of the other choses seem to get me there either..

is there a simple way to do what I'm attempting so I have this with me always?

thanks,

Whalstib

STATS > FIT DATA

You should see a screen that shows $$\sigma$$DAT, X-Col, Y-Col, and Model. Choose Linear Fit for the Model, and X-Col and Y-Col as 1 and 2, respectively. When entering data, make sure that the X values are listed in the first column, and the Y values are listed in the second column (as per your settings). Here's a sample data set:

(1,5) (2,10) (3,15) (4,20)

On the calculator, this should appear in the matrix editor as as:

1 5
2 10
3 15
4 20

Upon pressing OK, you should see:

$0.+5. \cdot X$
Correlation: 1.
Covariance: 8.3333333333

This means your "m" is 5. and your "b" is 0.