STDEV help

[enagy]

Could someone help me, please?
I have column A (timeline) and column B (corresponding heart frequency data).

We enter timepoint 1 into a cell (beginning of the measurement - entered into E1) and timepoint 2 (end of the measured period) into E2. I'd like to know the average heart rate for that given period and the STDEV of the heart rate data.
In E 3 we calculate the corresponding average of the heart rates :

[FONT=&quot][/FONT]=AVERAGEIFS(B2:B10000,A2:A10000,">="&E1,A2:A10000,"<="&E2)

I don't know how to calculate the corresponding standard deviations of the above data.

I would be very grateful for help, it is to make my students' work less easier in a psychology project.
thank you!

 

[Stiuart_W]

In column c add formula =(b2-$E$3)^2 (I have assumed that you have a header in A and B. then fill this down

In E4, say, enter = SQRT((sumifs(B2:B10000,A2:A10000,">="&E1,A2:A10000,"<="&E2)^2/countifs(B2:B10000,A2:A10000,">="&E1,A2:A10000,"<="&E2)-1)))

NB. I haven't tested this

 

[enagy]

Thank you, Stuart for the fast help. Unfortunately I get 'too few arguments for this function' note when I try to enter this.
Emese

 

[shg]

	A​	B​	C​	D​	E​	F​	G​	H​
1​	Point​	Time​	BPM​	​	​	​	​	​
2​	1​	12:32​	72​		Beg​	12:34​	3​	G2: =MATCH(F2, $B$2:$B$17)
3​	2​	12:33​	73​		End​	12:45​	14​	G3: =MATCH(F3, $B$2:$B$17)
4​	3​	12:34​	75​
5​	4​	12:35​	72​		Avg​		73.6​	G5: =AVERAGE(INDEX($C$2:$C$17, G$2):INDEX($C$2:$C$17, G$3))
6​	5​	12:36​	70​		SD​		3.4​	G6: =STDEV(INDEX($C$2:$C$17, G$2):INDEX($C$2:$C$17, G$3))
7​	6​	12:37​	68​
8​	7​	12:38​	70​
9​	8​	12:39​	71​
10​	9​	12:40​	73​
11​	10​	12:41​	75​
12​	11​	12:42​	78​
13​	12​	12:43​	77​
14​	13​	12:44​	77​
15​	14​	12:45​	77​
16​	15​	12:46​	76​
17​	16​	12:47​	78​

 

[enagy]

Thank you very much for this help, it works beautifully! I am very happy, thank you again!!!
Emese

 

[shg]

You're welcome.