Solved

sd and mean

Posted on 2006-11-11
6
369 Views
Last Modified: 2013-11-13
R5S RNA has a sequence of 120 nucleotides.  We replicate the new sequence 100 times and find there are 60 of A’s in the 20th position.   Suppose the probability of an A in the 20th position = 0.79 in R5S.

In this case, what is the sd of the sample and the mean of the genral population?

thx
0
Comment
Question by:ethanjohnsons
  • 4
  • 2
6 Comments
 
LVL 84

Expert Comment

by:ozo
Comment Utility
If the occurance of an A in the 20th position of each of the 100 replicas is independent (which seems like a strange assumption to me if they are replicated)
then the expected number of As in the 20th position would be a binomial distributuon with mean 0.79*100 and standard deviation sqrt(100*0.79*(1-0.79))
0
 

Author Comment

by:ethanjohnsons
Comment Utility
If I calculate t-value,

sqrt(100*0.79*(1-0.79)) = 4.073082

(0.79*100-60)/( 4.987484/sqrt(100)) = 38.09536

it is abnormally large.  What is wrong?
0
 
LVL 84

Expert Comment

by:ozo
Comment Utility
You should not be dividing by sqrt(100)
0
Highfive + Dolby Voice = No More Audio Complaints!

Poor audio quality is one of the top reasons people don’t use video conferencing. Get the crispest, clearest audio powered by Dolby Voice in every meeting. Highfive and Dolby Voice deliver the best video conferencing and audio experience for every meeting and every room.

 

Author Comment

by:ethanjohnsons
Comment Utility
then what would be the sample size (= sqrt( ??) here?
0
 
LVL 84

Expert Comment

by:ozo
Comment Utility
It depends what you are talking to be the sample size.
You are doing the experiment one time, so you might be saying
(0.79*100-60)/( 4.987484/sqrt(1))
of if you mean the number of 20th positions that may or may not contain A, then you would take sd=
sqrt( sample size *0.79*(1-0.79))
0
 
LVL 84

Accepted Solution

by:
ozo earned 500 total points
Comment Utility
Or if you want the average number of A's per 20th position,
then sd for one sample is 0.79*(1-0.79) and for 100 samples
mean = 60/100 sd = 0.79*(1-0.79)/100
0

Featured Post

Threat Intelligence Starter Resources

Integrating threat intelligence can be challenging, and not all companies are ready. These resources can help you build awareness and prepare for defense.

Join & Write a Comment

Suggested Solutions

Title # Comments Views Activity
Perecntage 4 51
Relative Frequency Assessment 2 27
Probability Distribution 5 35
Error in calculation 2 49
Dependencies in Software Design In software development, the idea of dependencies (http://en.wikipedia.org/wiki/Coupling_%28computer_programming%29) is an issue of some importance. This article seeks to explain what dependencies are and where they …
Exception Handling is in the core of any application that is able to dignify its name. In this article, I'll guide you through the process of writing a DRY (Don't Repeat Yourself) Exception Handling mechanism, using Aspect Oriented Programming.
In this seventh video of the Xpdf series, we discuss and demonstrate the PDFfonts utility, which lists all the fonts used in a PDF file. It does this via a command line interface, making it suitable for use in programs, scripts, batch files — any pl…
In this tutorial you'll learn about bandwidth monitoring with flows and packet sniffing with our network monitoring solution PRTG Network Monitor (https://www.paessler.com/prtg). If you're interested in additional methods for monitoring bandwidt…

728 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

12 Experts available now in Live!

Get 1:1 Help Now