Tagged Questions

4
votes
1answer
30 views

Population standard deviation for a binomial(?) distribution?

I have been confused by two separate questions (Stock & Watson - introduction to econometrics ch.3), using different values for standard errors. The first: In a survey of 400 voters, 215 respond ...
0
votes
0answers
19 views

Combining covariances

Imagine we have one sample (n=40) from a population on 2 variables, for which we estimate the covariance (say, 0.1). If we would have another sample (n=10) from the same population, and we estimate ...
1
vote
2answers
99 views

Population Variance and Sample Variance

How is it that lowering the number of frequence,$n$ by $1$ in the for formula for Population and Sample Variance account for the discrepency of using sample rather than population. I mean how is ...
0
votes
1answer
77 views

Population vs sample variance

This is perhaps a very basic question, but I am a bit confused. I have a time series of day some time varying data, say the amount of sunlight as the day passes. I bucket the data in say 10 bins say ...
0
votes
1answer
65 views

Identifying populations and samples from a dataset

I'm writing a proposal for a restrospective cohort study using registry data. Am I right to think of the registry data as the whole population? If it is the population, then am I right in thinking ...
4
votes
3answers
117 views

Confusion between sample and population

A team has conducted a study in which an introductory class was randomly divided into two groups. Group 1 was administered a dosage of alcohol. Group 2 was given an equvialent dosage of ...
0
votes
0answers
148 views

What is minimum sample size to get significant?

I want to test whether there are any significant differences between Public Relation Strategies of the companies listed in the Malaysia Stock Exchange. The total population is 825 companies within 13 ...
2
votes
2answers
2k views

Deciding whether to use r^2 or adjusted r^2 (specific situation)

I read online that it is only necessary to use adjusted-$R^2$ when you are working with a sample rather than the entire population. The data I'm working with is information on a series of live ...
3
votes
3answers
620 views

Identifying the population and samples in a study

I apologise for the silliness of this question. I ran an e-learning experiment using a class of undergrads. Participation was voluntary, so only half of the class participated. I know that my sample ...
1
vote
1answer
835 views

Testing for significance of difference between two populations

I am trying to test the significance of the difference between two populations. Here is a link to the population 1 data: http://pastebin.com/914mCRqA and population 2 data: ...
2
votes
1answer
118 views

In benchmark tests should I use formulas assuming a population or a sample?

I have a single JavaScript benchmark test that I run a number of times and store the results in an array. I then calculate the mean, variance, and standard deviation of the results of the runs. My ...
9
votes
3answers
21k views

What is the difference between a population and a sample?

What is the difference between a population and a sample? What common variables and statistics are used for each one, and how do those relate to each other?
56
votes
21answers
3k views

Locating freely available data samples

I've been working on a new method for analyzing and parsing datasets to identify and isolate subgroups of a population without foreknowledge of any subgroup's characteristics. While the method works ...