I did a biology experiment where I need to analyze the statistical significance of betweeen a data set. My experiment consisted of measuring the effects in photosynthesis and cellular respiration by exposing solutions with leaf discs to different light wavelength. Forthe statistical significance, I have to compare data I got with blue and green light to white light. The amount of discs for the time point I chose for blue was: 3, white: 23 and for green: 6 I'm supposed to use the chi square method to compare this values and I got 13 for my expected value between blue and white and 8.5 between green and white and then a chi square of 7.69 for blue/white and of 24.735 for green/white. Are those values right? I have to use this method for many other time points but if I have this one right probably I have the others right, same if I have it wrong, if they are wrong, please explain how to calculate it. Thanks
chi^2= (obs-exp)^2/exp <--- Formula I used
To determine if the obtained values are correct, we can check the calculations step by step.
The chi-square test can be used to analyze the statistical significance between different groups or categories. In this case, you want to compare the effects of different light wavelengths on photosynthesis and cellular respiration.
To compare the data you obtained from blue light and white light, and green light and white light, you need to calculate the expected values using the chi-square formula:
χ^2 = (observed - expected)^2 / expected
Let's start by calculating the expected values for the blue light and white light comparison:
- The total number of observations for blue light and white light is 26 (3 + 23).
- To calculate the expected value, you need to apply the proportion of each category to the total. In this case, the proportion of blue light (3 out of 26) is 3/26 ≈ 0.1154.
- Multiply the proportion by the total number of observations: 0.1154 * 26 = 3.
- The expected value for blue light is 3.
Now, let's calculate the expected values for the green light and white light comparison:
- The total number of observations for green light and white light is 29 (6 + 23).
- The proportion of green light (6 out of 29) is 6/29 ≈ 0.2069.
- Multiply the proportion by the total number of observations: 0.2069 * 29 = 5.998.
- The expected value for green light is 5.998, which can be rounded to 6.
Now, we can calculate the chi-square values:
1. For the blue light and white light comparison:
- The observed value is 3.
- The expected value is 3.
- Plug these values into the formula:
χ^2 = (3 - 3)^2 / 3
χ^2 = 0 / 3
χ^2 = 0.
2. For the green light and white light comparison:
- The observed value is 6.
- The expected value is 6.
- Calculate the chi-square value:
χ^2 = (6 - 6)^2 / 6
χ^2 = 0 / 6
χ^2 = 0.
Based on these calculations, it seems there might be an error in your values. Both chi-square values should be zero, indicating no significant difference between the observed and expected values.
To ensure accuracy, please double-check your calculations and ensure that you have used the correct formula. If needed, revise the calculations and recalculate the chi-square values to confirm the results.