How much sample size

Thanks for your question. If you want to make reliable conclusions on a monthly basis, you will need respondents each wave. I would leave out the customers in credit for that month to avoid any bias.

The calculator gave me as the representative sample size. What is the formula used to determine the representative sample size with that margin or error and confidence level?

Hi Kaye, this is the formula: first you calculate the sample size SS. Hi, I am doing an interview based survey of households for a minor research project. If there are 34, households, then what should be my sample size? Also, since it would be a personally visited survey, there will be hundred percent response rate. Kindly, guide me. You can use our sample size calculator to check for other options. Hello , I am not that much into stat but i really need to determine my sample size out of a population of , Can you please explain me how to determine my sample size?

You can use our sample size calculator to determine the required sample size. Hi, Thank you for your post. I had a question about the required sampling size. I am currently picking 3 out of 20 possible future scenarios and testing them in a model. However, this is a huge number and I would like to do only the minimum number of runs.

How would I determine this number? Thank you in advance! I have no straightforward answer for this specific question, I suggest you post this on a specialized statistical forum. Hi, If I have to report so what should the sample size be? Can you tell me what the stands for? Is that your total population? You can use our sample size calculator to calculate the required sample size for different populations, confidence levels and margin of errors. Hello, I am currently designing a community study using RCT in one district in my country.

The study is about assessing the impact of mobile screening on cervical cancer among rural women aged and this will be compared to standard care. In the district, we have 93 parishes. I will randomize at aggregate level using a 2- stage sampling implying my sample will be the parishes as the unit of analysis. Initially including all parishes and in stage two, I randomize the required number equally in the intervention and control arms.

What is the best formula for me to get the right sample size of parishes required. This is not a straightforward question and requires some advances statistics.

Hello- we are currently conducting a customer survey and I was wondering if the way we are currently doing is better than sampling the population. We have on average service tickets in the last 6 months. I am assuming this is the population size? Our response rate i. Is this a better number representative of the population or would sampling yield better response rate? Thanks for your interesting question. You also need to take into account the representativeness of your sample.

You need to have a representative spread over age, region, gender, …or try to at least. How would I determine the correct sample for auditng purposes at an individual level?

For example, if I have 10, widgets being processed daily and there are 50 people processing them, how would I determine the sample per person? This means you have an average of widgets per person. I am doing research on this ethnic population and needs to know how many people should i get for my subjects?

I would like to conduct a telephony survey to get an idea on how we are doing in our retail field for our furniture showrooms. I have a database of , customers. Could you advise how many customers i should be calling to participate in the survey? What are the parameters to know the effectivity of a machine in the ease of understanding of operation. I have 20 colleges with different no. As per your website calculator i have to select students out of 1 lakh.

I am going to conduct the baseline study of 3 districts. How can i calculate sample size. With known population of 3 distritcs. I have read lots of theories on determining sample sizes. But I would like to be assured on how to appropriately decide on the number of sample I will make from an CDs each containing to records and found out that there were some bad records. I got to learn a about the computation of Sample size but I would like to know a precise answer to my problem statement.

My problem statement is that I have a population which includes customers visiting my site from multiple devices and buying from a particular device and customers visiting and buying from same device. Main problem I am facing is that I am unable to classify the percentage of customer who is coming from multiple device and customer coming from single device but I want to estimate a number that can represent the entire population.

Can you please explain how this will impact the calculation of the sample size. Anyway, it does not impact the calculation of your sample size. You still need a number of respondents. However, it might impact the number of invitations you send out as you do not have to consider the response rate and thus send out more invitations.

Hi thank u for a really helpful website. Im conducting a research on the millennial generation in Pakistan who are on facebook for my M Phil thesis. That makes up around 2 million people. Now since the response rate is quite low questionnaires were sent four times the estimated sample size. Which was according to your website. Now after one month number of responses I got are However, there is a caveat.

How to calculate the number of product from line which have 10 machines and have cycletime of each workstaion? Thank you for your helpful website. I am conducting a survey with college faculty at 5 local area colleges, with a total population of full-time faculty. I am using a predictive correlational design and have 1 IV with four sub concepts and 1 DV with five sub concepts.

Will this give me a large enough sample size? I would calculate your sample size for each college separately, i. As such you will be sure that each college has a large enough sample size.

We want know awareness levels of cancer patients attending hospital in specific area of India having 4 crore population. What is the minimum sample size required for this study…? Supriya S. E-mail: moc. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

This article has been cited by other articles in PMC. Generally, the sample size for any study depends on the:[ 1 ] Acceptable level of significance Power of the study Expected effect size Underlying event rate in the population Standard deviation in the population.

P OWER Sometimes, and exactly conversely, we may commit another type of error where we fail to detect a difference when actually there is a difference.

Open in a separate window. Determining the sample size in a clinical trial. Med J Aust. Factors influencing the sample size, exemplified by studies on gastroduodenal tolerability of drugs. Scand J Gastroenterol. Response of Ayurvedic therapy in the treatment of migraine without aura.

Int J Ayurveda Research. Effect of early intervention with sumatriptan on migraine pain: Retrospective analyses of data from three clinical trials. Clin Ther. Support Center Support Center. External link. You think most people will give similar answers. The decisions that will be made based on the results do not have significant consequences. Choose a number closer to the maximum if: You have the time and money to do it.

It is very important to get accurate results. You plan to divide the sample into many different groups during the analysis e. You think people are likely to give very different answers. The decisions that will be made based on the results of the survey are important, expensive or have serious consequences.

She holds a Ph. Piroska is passionate about using scientific evidence and creativity to design programs that work. All rights reserved. Use the standard deviation of 0. Now that you know what goes into determining sample size, you can calculate sample size online. Or, calculate it the old-fashioned way: by hand.

Below, find two sample size calculations - one for the known population proportion and one for the unknown population. Try increasing your margin of error or decreasing your confidence level which will reduce the number of respondents necessary but increase chances for errors. Calculating sample size sounds complicated - but, utilizing an easy sample size formula and even calculators are now available to make this tedious part of research faster!

Now, it's time to recruit your sample and run a focus group or even a customer satisfaction survey. Whatever you decide, you now have the information needed to make decisions with confidence. Want to whip your research skills into shape?