Statistics question

rhlow

New member
Hello!

I have a question regarding calculating a standard deviation.

I have been taking plant measurements of a series of weeds. I had 4 plots in total, with 10 plants in the first plot, 3 in the second, 9 in the third and 13 in the fourth. Unfortunately I didn't take the plant biomass of each, rather, I took a total weight of each of the plants. As such, I have a total mass of 149.57 grams in the first plot, 12.91 grams in the second plot, 54.69 grams in the third plot and 23.47 grams in the third plot.

So when I calculate my standard deviation is my 'n' value 4, or is my 'n' value 35? I am wondering if I have limited my degrees of freedom by lumping the total biomass of all the pants in the plots.

Regards to all who respond to this! I appreciate it.

tkhunny

Moderator
Staff member
What are you trying to do? Is it significant that there are four plots or are you just planting where you have space?

rhlow

New member
The experiment has already been conducted, and there were 4 reps in the trial. This is just one portion of what I am looking for, I just didn't want to bog people down with numbers. Does that help?

Subhotosh Khan

Super Moderator
Staff member
Hello!

I have a question regarding calculating a standard deviation.

I have been taking plant measurements of a series of weeds. I had 4 plots in total, with 10 plants in the first plot, 3 in the second, 9 in the third and 13 in the fourth. Unfortunately I didn't take the plant biomass of each, rather, I took a total weight of each of the plants. As such, I have a total mass of 149.57 grams in the first plot, 12.91 grams in the second plot, 54.69 grams in the third plot and 23.47 grams in the third plot.

So when I calculate my standard deviation is my 'n' value 4, or is my 'n' value 35? I am wondering if I have limited my degrees of freedom by lumping the total biomass of all the pants in the plots.

Regards to all who respond to this! I appreciate it.
If all the conditions were same - you have 4 numbers and your n = 4.

There are procedures to deal with statistics of averages (in this case 14.957, 4.303, 6.115 and 1.806).

However, since the averages are so different - can you assume that those are from same population?

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