Sample size

Another thing I found interesting in this article is that Gallup as well as other major organizations use sample sizes of 1,000-1,500 because these sample sizes are enough to give a good balance of accuracy opposed to much larger samples which would be very expensive. I hadn 't considered expense when it comes to collecting a sample but apparently it can be very costly. For instance, if a sample size of 4,000 were selected each time there was a poll, the increase in accuracy would be very small, and

increase in sample size have on the margin of error of a confidence interval estimate? Explain your reasoning. An increase in sample size will decrease the margin of error of a Confidence-interval estimate. 3. a) A simple random sample of thirty-six students has a mean age equal to 25 years. Given =4.8 years, determine a 90% confidence interval estimate for µ. E ≤0.8, µ = 25 so The 90% confidence interval is 25 ± 1.32 = 23.68 and 26.32 b) Determine the sample size required to

School Environment to Make It Safer” draws upon qualitative research to explore the process of involving teachers and students in student action groups. The article draws on the qualitative process by using semi-structured interviews with a small sample of students and staff members (Fletcher, Fitzgerald-Yau,

Success of male yellow dung fly breeding. Introduction Looking at the yellow dung fly, Scathophaga stercoraria, it is seen that the species experiences sexual dimorphism in the form of both size and colour. This gives changes between the males and females that are specially adapted to give them the best chance of producing offspring. Males are considerably larger than the females and have clearly defining yellow hair along the abdomen, whereas females are smaller and are more of an olive green colour

of characteristics is most likely to produce a significant t statistic?  n = 50 with s^2 = 50 If other factors are held constant, what is the effect of increasing the sample size? It will decrease the estimated standard error and increase the likelihood of rejecting H0 A researcher conducts a one-sample hypothesis test using a sample of n = 40 from an unknown population.  What is the df value for the t statistic? 39 With α= 0.05, what is the critical t value for a one-tailed test with n = 15? t =

A hypothesis is a point of research for evaluating the sources of data in either a controlled or uncontrolled experiment using variables. An hypothesis is the prediction that requires the process of being proved of being false or true (Bowles, 2013). A hypothesis must be clear and simple to understand that states the purpose of a test. It must contain logical and be testable. The hypothesis defines what data variable are considered for testing. The development of a hypothesis begins with identifying

determine just how expensive a cappuccino was in San Francisco, I sampled cappuccino prices at 36 coffee shops scattered across San Francisco. The sample mean price of a cappuccino is $3.54 (x̅) with a sample standard deviation, or a standard error, of $0.55 (s). The prices ranged from $2.50 to $4.40. To construct a 99% confidence interval for this sample, I multiplied the standard error by the z-statistic corresponding with 99%, 2.576, and added/subtracted that value from the point estimate, $3.54

number of hours a week he/she reads a newspaper. The sample mean was 4.1 and standard deviation 3. We can assume that the underlying distribution (of number of hrs reading newspaper) is approximately normal. a) What will be a 99% confidence interval of the population mean (number of hours a B-school student read newspapers/week)? b) Suppose you perform a similar survey at IIMA with 24 randomly selected students; the sample mean and the sample standard deviation were 4.5 and 2.8 respectively. What

procedures will data collectors need to follow? Steps in Selecting a Sample-Size An appropriate sample size is based on a number of accuracy factors that you must consider. Together they comprise a five step process: 1. Determine Goals 2. Determine desired Precision of results 3. Determine Confidence level 4. Estimate the degree of Variability 5. Estimate the Response Rate Step One: Determine Goals • First, know the size of the population with which you’re dealing. If your population is small

In one case, a client provided Quality Associates with a sample of 800 observations that were taken during a time when the client's process was operating satisfactorily. The sample standard deviation for these data was .21, hence, the population standard deviation was assumed to be .21. Quality Associates then suggested that random samples of size 30 be taken periodically to monitor the process on an ongoing basis. By analyzing the new samples, the client could quickly learn whether the process was