# Tagged Questions

42 views

### Testing to see if a population is normal?

I'm an amateur statistician. I do it mostly for fun. I'm finishing up on my first semester stats class that covers up to hypothesis testing. I'm planning on beginning learning simple regression ...
58 views

### Why describe a sample as i.i.d.?

I’m hoping for some help understanding the concept of RVs with respect to their use in the theory of drawing inferences on a population from a sample. To draw inferences on a population using a ...
33 views

### Need to verify sample is representative of known population of animals

I'm a biologist trying to verify that the age, gender, and family group of my samples from a population of whales is representative of the population, in order to make inferences in the discussion. ...
56 views

### Standard Deviation and Variance in Sample and Population Formulas for all?

What are the differences between those Population and Standard Deviation and what are their fomulas? I was told that they are different formulas and which situation do you use population or sample? ...
10 views

### Quantitative ,longitudinal, observational study:Population, sample and instrument

I am studying US public company financial performance for the last 2 decades. I am searching for evidence of "sustainable superior performance", thus to isolate those companies that display such ...
52 views

### When do we calculate the population parameter instead of sample statistics?

When do we calculate the population parameter instead of sample statistics? If there is a this kind of case which statistical tool should we use population parameter or sample statistics? A car ...
72 views

### How to deal with non random samples?

I have a specific question about random selection, representativeness and inference. It is well known that it's necessary to use random selection to get representative samples from the population of ...
35 views

### Appropriate way to estimate sample size requirements for an unknown population distribution

Assuming we have a sample (some observables) from a population of unknown distribution, can I assume that the right way to estimate the sample size (for estimating means, medians, etc.) is using the ...
121 views

### Is my sample representative of the population I am trying to measure?

We have completed a survey of FTSE350 companies, but only received 49 responses. We assume that this response rate means that our results are not representative of the FTSE350 as a whole, but wanted ...
598 views

### SPSS: “Weight cases” by multiple factors, by taking the product of weights?

My understanding is that a sample can be adjusted based on a known population using the "Weight Cases" function in SPSS. What is the proper procedure for weighting by multiple factors? Let's say I ...
201 views

### Is any quantitative property of the population a “parameter”?

I'm relatively familiar with the distinction between the terms statistic and parameter. I see a statistic as the value obtained from applying a function to the sample data. However, most examples of ...
121 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 ...
48 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 ...
174 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 ...
124 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 ...
94 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 ...
133 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 ...
166 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 ...
4k views

### Whether to use r-square or adjusted r-square with a small sample size that may represent the entire population?

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 ...
863 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 ...
1k 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: ...
155 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 ...