Hi Amedee,

It sounds like you have a challenging data analysis task ahead of you, but don't worry, there are a few ways to approach this problem in Excel. Here's one possible solution:

1. First, create a scatter plot of your data points. Select the data range, go to the Insert tab, and choose Scatter from the Chart group.
2. Next, add a new column to your data table that calculates the time of day for each data point. For example, if your data starts at 12:00 AM and is collected every 5 minutes, the first time value would be 0, the second would be 0.0833 (5/60), and so on. You can use the following formula to calculate the time value for each row:
   Formula:

   =MOD(A2,1)*24 

   , assuming your time values are in column A.
3. Now, create a new column that calculates the sine of the time value, using the following formula:
   Formula:

   =SIN(B2*2*PI()/24) 

   , assuming your time values are in column B and the period is 24 hours.
4. Add a new scatter plot series to your chart, using the time and sine columns as the X and Y values. This will create a smooth sine wave line on your chart.
5. To calculate the amplitude of the sine wave, you can use the MAX and MIN functions to find the highest and lowest points of the sine wave, and then subtract them to get the amplitude. For example, if your sine wave values are in column C, you can use the following formula:
   Formula:

   =MAX(C:C)-MIN(C:C) 

   .
6. To calculate the error margin of the amplitude, you can use the STDEV function to calculate the standard deviation of the sine wave values, and then multiply it by 2 to get the 95% confidence interval. For example, if your sine wave values are in column C, you can use the following formula:
   Formula:

   =STDEV(C:C)*2 

   .

Let me know if you have any questions or if there's anything else I can do to assist you.