1. N

    Appropriate Sample Size

    Hi all - I'm very new to stats so looking for help with a problem I'm having. Any resources or tips would be greatly appreciated! I have a huge population dataset under different categories. This dataset contains one record per person, and has the following qualities: MEMBER_ID (one record...
  2. S

    Essay Question

    Hello all, I have to write an essay at the moment and unfortunately I am stuck on a question, maybe you can help me with it. The question is as follows: "Describe in your own words how an approximation method that determines a confidence interval for the mean of a population from a sample can...
  3. R

    Sampling Twitter Accounts

    Hello, I need to do a content analysis of certain types of Twitter accounts. There are in total 19 of them (N = 19) but I need to take a sample due to resource constraints. I want to have 95% confidence (Z = 1.96) and a margin of error of 5% (E = 0.05). In order to understand the variability of...
  4. M

    Mechanical Engineering Sample Test Size

    You need to conduct an engineering 3-Point Bending. How many samples should you test? I was recently asked this in an interview but was not sure how to answer. I tried saying that it would depend on time, the readiness of the samples, and the cost of the tests but the interviewer said to...
  5. C

    Sampling Plan Help

    Hi! I'm new to the forum. Hopefully this is the right place to post for some assistance. I have a business partner that asked about control charts, but I think he is looking more for an acceptance sampling plan. I have done this in the very distant past, but it's just been too long... :(...
  6. S

    Extrapolation - Getting info of a population from a sample

    Hello, I'm working on a problem where I have 30% of a full dataset and I have to estimate the generalization error. To be more precise, let's say I have the information of the transactions of the clients of a bank which has 30% of the countries market. I can easily get the mean, standard...
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  9. S

    Sampling Distribution Problem

    Roll a dice five times. Record the results in Sample 1. Repeat the experiment for Sample 2, 3, and 4. In a live classroom setting, actual survey data is used. In this knowledge check online environment, please use the following data: Sample 1 Sample 2 Sample 3 Sample 4 2 4...
  10. S

    Is this conclusion drawn from sample or population?

    "When asked what they would use if they were marooned on an island with only one choice for a pain reliever, more doctors chose A than B, C or D." Is this conclusion drawn from population or a sample? I am confused here because how do we know if on an island there were all the doctors that...
  11. R

    Is there a way to increase power in my study

    Hi everyone, I'm working on my 'behavioral change' master thesis. My goal is to design an intervention to reduce printing at the workplace in a big organisation. Unfortunaltely i dont get provided with the printing details on a personal level, so my best bet is too see how much a printer...
  12. Z

    Correlation evaluation

    Is there a single statistic which can reflect the different importance between similar correlations, say 0.7, based on different sample sizes such as n=10 and n=1,000?
  13. J

    Commenting on wider population from survey sample

    I am conducting a survey in 9 restaurants, hoping to gather data on our customer demographic profile. The population is equal to the number of covers the restaurant had over the corresponding period in the previous year. This ranges from 4000 to 10000. Across all sites then, I understand that I...
  14. I

    The Unexpected and Thrilling life of Grass - A Statistical Story

    Hi, I'm an aspiring Environmental Scientist and i've recently finished some data collection to do with Common Grassland Species. My hope was to match my findings against a Botany report done several years ago to see the change over time. However i can't figure out which tests to use as most...
  15. L

    Calibration set for PLS regression

    Hello everyone, New to this forum and kind of wondering why I hadn't thought to search for one before tonight... I hope a light at the end of the 'searching literature tunnel'. Briefly, I use PLS regression to model spectroscopic measurements of plant material. That's probably neither here...
  16. N

    Help with errors in a research

    Hi all, I am new to this forum and I am really glad that I found it. Hope I'll be able to offer some help as well. My problem is fairly simple, but I couldn't find the answer anywhere and my attempts were very poor. I am doing analyses on some soil samples and I am getting an analytical...
  17. L

    Sampling issue

    I want to be able to make comparisons between a specifically selected sample (based on ethnicity) and a randomnly selected sample from the general population. Even though the specific ethnicity represents no more than 10-15% of the population, my randomnly selected sample from the general...
  18. 2

    Quick Population / Media Prob question

    This is hopefully a fairly quick conditional probability question for you guys. Imagine a total population of 22MM people and I am running a media campaign against 2MM of those people. Secondarily, a survey company has access to a random sample of 4MM of the 22MM population. Each week...
  19. A

    Sampling distribution of the sample proportion.

    A random sample of 20 students is selected. What is the probability that the sample proportion exceeds 75%, i.e., more than 15 students (out of 20 selected) will agree that that the course is interesting? You may leave your answer as, for example, 1 − 0.88. (As a standard error use 0.8. Also...
  20. T

    Standard Deviation

    You select a random sample of n = 14 families in your neighborhood and find the following family sizes (number of people in the family). 15, 16, 16, 15, 19, 16, 18, 15, 17,16, 15,17,16, 18 I found the mean family size which is 16.4. To find the mean family size, I added up all of the...