# Tagged Questions

12 views

### How to calculate the percentage difference taking 95% CI into consideration?

I now have two averaged numbers, say $a$ and $b$. $a=1.1$ with 95% Confidence Interval of $\pm0.2$ and $b=1.0$ with 95% Confidence Interval of $\pm0.1$. Is it reasonable to calculate their ...
38 views

### What is the appropriate test for comparing means?

I have a case and control group, both of which had a blood sugar level tested multiple times over 48 hours. I took the mean of the levels for each person and then calculated the mean of the means ...
181 views

### Construct confidence interval of the mean for auto-correlated data

I feel like I'm missing something obvious, but here we go. I have auto-correlated data measured in triplicate for two (or more) treatments. Something like this: ...
84 views

### Finding the mean difference of two data sets in R, within a confidence interval

I'm analysing benchmark data for some of my R functions, and I'm trying to compute a statistic describing how many times faster my function - group_one - is than a control function - group_two - as a ...
87 views

### How to add prediction intervals to describe the variability in monthly samples of data?

The data analyzed here is a sample of individuals collected on a monthly basis. What would be the best way to compute "prediction intervals" for the monthly sample means, in order to indicate the ...
99 views

### Why do we refer to our estimates in terms of precision?

Open any statistics textbook and it will urge the need to check the 'precision of our estimates'. Take the following random variable: ...
144 views

### What should I do when a confidence interval includes an impossible range of values?

Let's say I'm analyzing the mean number of students per class for a school district. The district has imposed a hard limit on the maximum ratio: there can never be more than 30 students in a class. ...
47 views

### Calculate proportion among means with variance and CI

I have two groups of samples, with their own mean, SEM, CI. I would like to calculate the proportion in percentage between the two. Rationing the means is easy but I don't know very well I should I ...
660 views

### What is the correct SD to use to get a 95% CI for skewed data?

Let $X = [94, 10, 100, 100, 16, 14, 100, 100, 70, 88, 100, 100, 12, 100, 100, 58, 32, 100, 32, 36, 98, 0, 100, 100, 100]$ where $X$ are students' scores (between 0 and 100), and note many full marks! ...
3k views

### How do I calculate a confidence interval for the mean of a log-normal data set?

I've heard/seen in several places that you can transform the data set into something that is normal-distributed by taking the logarithm of each sample, calculate the confidence interval for the ...
828 views

### How to assess accuracy of phone GPS in measuring distances?

I am a complete stranger to statistics (apart from mandatory courses in college), but lately I ran into an interesting real-world scenario. Recently I started jogging. I take my GPS phone with me to ...
230 views

### Confusion regarding the confidence interval

I have some confusion regarding confidence interval. I was going through this link http://www.stat.yale.edu/Courses/1997-98/101/confint.htm It has something like this: Suppose a student ...
199 views

### Real data collection with small population

I performed an actual scientific experiment and I was only able to collect 2 data points. I am wondering what kind of statistical method I can use to analyze the data. I performed a similar ...