How big should sample groups be?
A good maximum sample size is usually around 10% of the population, as long as this does not exceed 1000. For example, in a population of 5000, 10% would be 500. In a population of 200,000, 10% would be 20,000.
What are unequal sample sizes?
Unequally sized groups are common in research and may be the result of simple randomization, planned differences in group size or study dropouts. Unequal sample sizes can lead to: Unequal variances between samples, which affects the assumption of equal variances in tests like ANOVA.
How to prepare data for sample from groups?
Illustrated with the iris data. Species = groups. Sample from the 3 Species with 3 different sample sizes. DRAW A SAMPLE for each PAIR OF (SPECIES DATA, SPECIES SAMPLE SIZE) How to prepare the data? I need a data frame with A variable of Species -specific sample sizes A variable of “Species data”, whatever that means.
How can I compare groups with unequal sample sizes?
One group is n=4 and the other is n=68. The n=4 group doesn’t have enough subjects to really test for normality so I’m not sure if a t-test for independent means will work. I’m thinking probably a Mann-Whitney U test. Any suggestions? Is it even possible to compare the means between the two groups with such a difference in size?
Which is a variable of species-specific sample sizes?
A variable of Species -specific sample sizes A variable of “Species data”, whatever that means. Actually we know what that is: a variable of Species -specific data frames. A list-column! We need a nested data frame. Draw the samples. purrr::map2 () is good since we want to operate on 2 things (data = DATA FOR ONE SPECIES, n = SAMPLE SIZE).
Is the sample size too big or too small?
Although at first blush it may seem like an overriding concern over methodological issues, notably to clinicians, such concern is utterly justifiable. This issue is of paramount importance. Samples should not be either too big or too small since both have limitations that can compromise the conclusions drawn from the studies.