SIZE CORRECTLY! EMAIL: [email protected] CELL #: (333) 2336 984 FOR ANY QUERY & CONSULTATION PLEASE VISIT: www.eyedeafoundation.org Sample Size Introduction: Everything is present in an enormous quantity in the universe, however we blame that we are living in scarcity. For instance human beings are uncountable and we cannot meet each and everybody intuitively in short time. If we want to establish that how many people like mango fruit or how many people like cricket game. To establish this we have to take small number of people randomly. Obviously we have not time and money to approach each and everybody for this, right! For another example we usually check the rice by eating only small chunk and we can decide its taste, right! Let take this if we want to check the bullet quality we do not have to fire each bullet to establish that bullets are OK! Sample Size Significance: Ideal thing is that we should have sample size equal to the population size, however it is not always possible on practical grounds. Calculation of sample size is an art. It’s very necessary to know the accurate number of sample size which can represent the true population. So we have to determine it very precisely. Sample size and power of the research has direct relation. Means if we increase our sample size the more will be the accurate result or more will be the true representation of the population. Some Index journals has the criteria of specific sample size if you want to publish your research article. In short we have to make sure that our sample size is large enough to be published and will determine true depiction of the population. Sample Size Steps: Fortunately, Eyedea Research Group has formulated the step by step simple approach for calculating clear-cut sample required for the research. Eyedea 7-STEPS Steps No. 1: Idea Clarification: First of all we have to make clear our idea of the research, which we are going to explore. Eyedea Research Group is ready to help for idea amplification for youngsters. If we have clear mind regarding the idea we can determine sample size easily. For instance our research area to check the consumer behavior of customer for Mobile phone purchase. For this we have to search our sample from the Mobile phone markets, however we can find our sample anywhere. Because now everyone has the Mobile device so we have to make sure that we have to collect the large number of samples to establish our results. For this we have to give more resources and time but less efforts. Conversely, if we want to establish that how many people have purchased mangoes by ordering online? For this we have to give more resources, time and efforts also and obviously only small number of sample we can find, right! Steps No. 2: Population: After clarification we have to understand that what our overall population size is. Our sample size should be as near as possible to the population size and in ideal condition sample should be equal to the population size. For this we have to see the demographics of our selected population. For example if we want to know about school going children in Pakistan, our population size will be the total number of school going children in Pakistan. Obviously, you should not take strain because even government of Pakistan is not sure about this number. So we have to take approximation and for this we have to go for the sample size. Commonly, population is to be unknown or estimated. Steps No. 3: Margin of Error: It is also called Confidence Interval and written as CI. Intuitively every sample may or may not be perfect, because we have to take only a chunk from the population. For this reason we have to take decision to allow the approximated error. The confidence interval defines how much lower or higher than the population mean we are willing to let our sample mean to fall. If you have ever seen a cricket match and you have to give answer online voluntarily that either Pakistan win or lose today. There is usually mini poll survey on the news, you must have seen a margin of error or confidence interval in it. For example 78% of voters said “Yes” to win, with a margin of error of +/- 5%.” Steps No. 4: Confidence Level: It is our confidence level which we want to decide that the actual mean should fall within our confidence interval. It is denoted by CL. The most common confidence intervals are 90% (usually taken for political polls), 95% (usually taken for everyday research) and 99% (usually taken for quality and standard setting research). Steps No. 5: Find Z-Score: Now it’s time to take the corresponding Z-Score. Fortunately, it is a constant value. So do not need to calculate or remember. For three confidence levels mostly used Z-Score values are as below: Z-Score for 90% Confidence Interval = 1.645 Z-Score for 95% Confidence Interval = 1.96 Z-Score for 99% Confidence Interval = 2.326 Note: If you have picked a different confidence level, use the Z-score table to catch your Z-score. Steps No. 6: Standard Deviation: It is our expectations that we consider for variance in our responses. It is usually decided beforehand or before conducting the actual research survey. Frequently the most précised and safe decision is to use 0.5 for our research. It is the utmost lenient number. It guarantees that our sample size will be large enough. Steps No. 7: Calculation: Take a deep breath and relax now we are ready to calculate our sample size! Formula: Sample Size = (Z-score)² * SD*(1-SD) / (Margin of Error)² Let’s Take: Confidence Level=95% Z-Score=1.96 Standard Deviation=0.45 Margin of Error= +/- 5%=0.05 By putting the values: Sample Size= [(1.96)² x 0.45(0.5)] / (0.05)² Sample Size= (3.8416 x 0.225) / 0.0025 Sample Size= 0.8643 / 0.0025 Sample Size= 345.744 Good Job! According to our calculation we need only research. 346 participants as sample size for our If you find your sample size is too large to handle, attempt to some extent by decreasing your confidence level or increasing your margin of error. Obviously, the chance for error will be increased in your sampling, but it can greatly decrease the number of samples you needed. Need help finding a qualified panel for your survey? With our valuable Eyedea Research Group experts, we are ready to find your target population, sample size solutions, in marginally low cost! 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