Please help. I need the exact computation for my study. You can check with our sample size calculator. I want to do a survey of 80 respondents randomly. Then what will be my sampling formula? If you have sample size 80 tyou can calculate backwards for a given population, confidence level and margin of error. Or you can use our sample size calculator for immediate result.
Hello Van Dessal. I sow the formula for unknown population. But my concern is that, the sample size needs to be distributed in four strata. Now, how can I divide it while the population is unknown? You will need to make an estimation of your population and try to divide your sample in 4 representative subsamples. You can always look for more detailed information on the subject in specialized statistical fora.
Hi, please assist me to compute sample size for a house hold survey where the number of house holds in the region are for my paper also consider giving me the formula to use. Do you mind giving it to me? How big of a sample size within each category would be needed to get a proper benchmark? I was thinking but wanted to get your opinion. Thank you! Hi Geoff, sorry for thte late reply. The margin of error for a sample size of depends on the size of your total population.
You can check for different population sizes using our sample size calculator. Hi, we are about to conduct a survey. We have a total population of customers. How many customers should be invited to answer our survey? Sorry for the late reply. You can use are sample size calculator to calculate your sample size for different confidence levels and margins of error.
Hello, I am doing a survey research on 90 nos. If you want to draw conclusions about households in the area, you should use the population size of 27, to survey different households and compare them. If you want to survey individuals and compare results based on socio-demographics age, gender you should use the general population to calculate your sample size.
You can calculate sample sizes using our online calculator. Am using a sample size of respondents in an Hospital setting with available sampling technique. What type of formulae method can I use. Thank sir. To calculate your ideal sample size you need to make an estimation on the total population first.
For large populations e. You also have to choose the confidence level and margin of error you want to allow. Hello Sir. I would like to calculate a minimum sample size for pedestrian populations nearly equal to Remember I planned to use convenience sampling. You can calculate this using our online calculator.
This number can also be used for a convenience sample. It indicates how much respondents you need to get a representative sample. Thank you so much for this helpful article. Please note that my sample will be a stratifed sample Thanks HAQ.
You can calculate your sample size using our sample size calculator. The sample size of your research will depend on the margin of error and confidence level you want to use. The higher these numbers, the more respondents you will need. The margin of error tells you how much the opinions of your sample are likely to deviate from the population.
This number is quite high. You can calculate your ideal sample size using our calculator. In that case you might al well use the entire population for your research. How I can calculate sample size? Pls tell me the formula of calculating sample size. First of all you have to make an estimation on the total population, e. Is it okay to use the slovin formula?
Since you have respondents which is your sample you might want to check whether the margin of error is acceptable or not. You can use the second part of our online calculator to calculate the margin of error for your sample size by filling in population size, number of respondents and confidence level.
Good morning sir. These fluctuations and variations are caused by erratic and irregular actions that are the result of random chance. These random variations cannot be eliminated or determined In fixed variation, the variation stems from fixed occasions, persons or groups. You also need to check whether your sample is representative of your total population. To calculate the sample size, you can use our sample size calculator.
P stands for the proportion you expect for the question you are investigating. Hi, I am trying to determine what sample sizes needed- we are carrying out a quality improvement survey with patients in 40 hospitals wherein the number of patients range from aprox ,, giving a total population of 33, patients across all hospitals.
We want to be able to present results at a national level and at a hospital level comparing across hospitals. I am just not sure do I have to create my sample size per hospital using the population within the hospital? Would really appreciate help! So you will have to calculate sample sizes per hospital. This of course will make your required total sample size considerably higher than when you only want to look at a total level.
You could also group hospitals per region and compare regions if you want to put a limit on your sample size. Please I just to know the author of sample size calculator. I also need to know if there is some document about it that i can refer? This is based on a formula that is commonly used for all sample size calculators on the internet and can be found in most statistical manuals. You can use our sample size calculator to calculate you sample size for different confidence levels and margins of error.
Dear sir I want to conduct survey on small and medium enterprise where in there are around SMEs in my universe. For small populations you almost need to include the entire population in your sample to get a reasonable margin of error. Dear sir i want to conduct a survey in a town, i have counted the number of houses per location and i got the total number of houses in the Town, but im struggling to get the minimum sample size for all the population or probably the acceptable sample size.
Numbers Of locations in town Number of houses per location 1. You can use our sample size calculator to calculate your sample. If you want to draw conclusions per location, you will need to calculate your sample size also per location.
If you only want to analyse globally, you can take the total of as population and spread your sample size proportionally over the locations. As the result, i only gather samples. Is it accurate since the total sample are different? And what theory supports it. Thank you very much.
You will see that with a large population, the denominator in the formula to calculate SSadjusted is close to 1. Be sure to make your selection of regions representative e. What I want to ask is, are there any ways I can use these response rates to calculate strata sample sizes? Or do I have to find mean value of response rate and use it to calculate for overall sample size? If you want ot treat your stratea as separate populations, you also have to look at them separately and calculate sample sizes per stratum.
And thus use the specific response rates you have estimated based on past projects. If you want to look at the total results of all strata as a whole, you can use the average response rate. I want to know the sample size of my survey. Because the mutual fund investors in India is unknown population so i need your help to determine sample size.
If you have a smaller population you will have to make an estimation. You can calculate the required number of respondents with our sample size calculator. Hi, What is the best way to calculate the sample size so yhat it is repreentative of the population in the following case.
There are 3, total customers and on a monthly basis the ones randomly selected will fill a survey. The ones asked to fill it, will all fill it. 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? In practice most people normally want the results to be as accurate as possible, so the limiting factor is usually time and money. In the example above, if you had the time and money to survey all students then that will give you a fairly accurate result. In that case you can use the following table.
Simply choose the column that most closely matches your population size. You will see on this table that the smallest samples are still around , and the biggest sample for a population of more than is still around The same general principles apply as before — if you plan to divide the results into lots of sub-groups, or the decisions to be made are very important, you should pick a bigger sample.
Note: This table can only be used for basic surveys to measure what proportion of the population have a particular characteristic e. See Sample size: A rough guide for other tables that can be used in these cases. Photo by James Cridland. This advice is for: Basic surveys such as feedback forms, needs assessments, opinion surveys, etc. Surveys that use random sampling. This advice is NOT for: Research studies conducted by universities, research firms, etc.
Complex or very large surveys, such as national household surveys. As we have noted before, when selecting a sample there are multiple factors that can impact the reliability and validity of results, including sampling and non-sampling errors. When thinking about sample size, the two measures of error that are almost always synonymous with sample sizes are the confidence interval and the confidence level.
Confidence intervals measure the degree of uncertainty or certainty in a sampling method and how much uncertainty there is with any particular statistic. In simple terms, the confidence interval tells you how confident you can be that the results from a study reflect what you would expect to find if it were possible to survey the entire population being studied.
The confidence level refers to the percentage of probability, or certainty that the confidence interval would contain the true population parameter when you draw a random sample many times. It is expressed as a percentage and represents how often the percentage of the population who would pick an answer lies within the confidence interval.
The larger your sample size, the more confident you can be that their answers truly reflect the population. In other words, the larger your sample size for a given confidence level, the smaller your confidence interval. In calculating the sample size, the standard deviation is useful in estimating how much the responses you receive will vary from each other and from the mean number, and the standard deviation of a sample can be used to approximate the standard deviation of a population.
The higher the distribution or variability, the greater the standard deviation and the greater the magnitude of the deviation. For example, once you have already sent out your survey, how much variance do you expect in your responses?
That variation in responses is the standard deviation. The other important consideration to make when determining your sample size is the size of the entire population you want to study. A population is the entire group that you want to draw conclusions about.
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