# quiz 2 notes - Sample subset of population take because...

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Sample- subset of population take because entire population too large to analyze. Mean- arithmetic- sum of values in sample divided by # of values in sample Median- separating higher half of sample from lower. Arranging values from lowest to highest and taking middle one Variance- measures dispersion around the mean Standard deviation- measures dispersion around mean but in same units as value Sampling Error- occurs if difference in value (error) between population parameter and sample statistic because of sampling Sampling Frame error- occurs when sample is drawn from an inaccurate sampling frame Standard error- estimate of stdev of sampling distribution Managerial Problem - mission, purpose, issue, or solution that will better the business. What should I do as manager-operational A larger sample can yield more accurate results, but excessive responses can be pricey. Set of all samples of size n that can be taken from a population Research questions - statements of what specific info required for progress towards achievement of research purpose. Shared understanding between manager and researcher (what information do I need to gather) Survey- data collection using a list of questions aimed at extracting specific data from people by asking questions. Done face-to-face at home, in school, work, sent in mail Experiment- study in which conditions are controlled so that one or more independent variables can be manipulated to test a hypothesis about a dependent variable. Population Size — How many total people fit demographic? Margin of Error (Confidence Interval) —need to decide how much error to allow. Confidence interval determines how much higher or lower than population mean willing to let sample mean fall Confidence Level — How confident do you want to be that the actual mean falls within your confidence interval? Confidence intervals are 90% confident, 95% confident, and 99% confident. Standard of Deviation — How much variance do you expect in your responses? Safe decision to use .5 –most forgiving number and ensures sample will be large enough. z-score (constant number depends on confidence level and can be found in a z distribution table. 90% – Z Score = 1.645, 95% – Z Score = 1.96, 99% – Z Score = 2.576 Necessary Sample Size = (Z-score)² * StdDev*(1-StdDev) / (margin of error)*** multiply calculated sample size by 1.2 since want bit larger in case of mistakes Don’t have budget for sample size? Try slightly decreasing confidence level or increasing margin of error –increases chance for error in sampling, but can greatly decrease # of responses needed.

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