Hello all. I found this site through a websearch and I am hoping someone can help me out.

I am trying to find out the most appropriate method for interpreting some data.

This is a current ongoing research project so I will use an analogy.

So here is what I am trying to show.

Left handed people have a higher likelihood of developing arthritis than right handed people. I have divided my patients into 4 groups.

Group 1: patients 40-49 years old with arthritis

Group 2: patients 50-59 years old with arthritis

Group 3: patients 60-69 years old with arthritis

Group 4: patients >69 years old with arthritis

A = LEFT handed

B = RIGHT handed

Now, I am also using the knowledge that 10% of the population from which I am getting my sample is LEFT handed.

SO...I would think that if my data shows that more than 10% of the people in my study are LEFT handed, this would be significant. Correct?

Here is my problem.

Thus far my data is coming out where close to 50% of the people who develop arthritis are LEFT handed. WOW! 5 times what I anticipated based on the percentage of LEFT handed people in the general population.

NOW>..how do I break down the data to show this is statistically significant?

Here is my RAW data:

Group 1: A = 3 B= 5

Group 2: A = 5 B = 3

Group 3: A = 6 B = 6

Group 4: A = 3 B = 4

N = 35

Total A = 17, Total B = 18

Again, with 35 people in the study and 10% of the general population being left handed, I would think that a random sampling of arthritis patients would be 10% lefty and 90% righty. But my data does not show this.

My data is showing that DESPITE the fact that most people are right handed, patients with arthritis are split down the middle.

Therefore, being LEFT handed increases your chance of developing arthritis versus a right handed person. Correct?

I think my reasoning is correct, but now I need to prove the data is statistically significant.

So I did a Chi Square...not sure if this is the correct method.

When I did the Chi Square and calculated the "Expected", my Significance came out to 0.77 with a Chi of 1.115 and Df = 3.

When I did the Chi Square and ASSIGNED the "Expected" based on what I would think would happen based on the fact that 10% population is lefty, 90% righty...my significance came out to 0.002, Chi of 14.496 Df of 3.

Is this the correct way of doing this? Simply assigning values in the "expected" square based on population trends, or do I need to calculate it using a formula? Is a chi Square the proper way to interpret this data?

ANY help would be greatly appreciated.

This is the last hurdle in moving forward with further write up and analysis.

Thank you so very much!