chi square

I have a question regarding goodness-of-fit tests. A general rule of thumb with the chi-square test of goodness of fit is that (1) no more than 20% of your expected frequencies can be less than five, and (2) none of your expected frequencies can be less than one. However, I am dealing with a...

Hey, I have some questions about which test I can or have to use. Which test do I use to only identify if there is a relationship between those variables? I only want that to know, for the identification of confounding factors. Ordinal dependent categorical variable <-> ordinal...

Hi, I am new to this forum so please be kind :-). Not sure if this belongs in 'R'. I will describe my problem as good as I can. First of all I am using R commander for my Master Thesis. My Thesis is to identify if there is an association between one predicting variable (categorical 'less...

Good Morning, I’m wondering if you could possibly help me with a little problem. I have some data: 1. Number and date of disease outbreak each year 2. Date a warning system for this disease occurred each year based on environmental factors. I would like to get a p value...

Hi, I realize this question might have been asked before, or is very rudimentary, but I'm having trouble figuring it out. I have several data sets (~50) comparing outputs from two different brands of product from different areas of the country. The issue I'm coming across is that for Brand A I...

I am trying to figure out a chi square problem, and I keep getting stuck. The problem reads: A researcher tested single mosquitoes from five different locations for the presence of a particular virus and obtained the following data: Location A B C D E w/ virus 3 7...

Hello everyone, I am having a problem comparing proportions between groups. My problem: A mouse can enter door A or B. I have two groups. In group 1, 90% of mice enter door A, in group 2, 55% of mice enter door A. I want to test whether there is a difference in the proportions of entering...

Hello, thank you very much in advance for any that can help me here I am looking to test the likely existence and the strength of the bulemia-suicide association among a database sample. (2) Key recent studies in this field’s have suggested that certain socioeconomic factors, living alone and...

Hi everyone... Please help me with the following question I'm doing my research that one of it aims is to test the model fit of a particular model. I'm having a problem to draw the conclusion of the fit of the model since it has various model fit indices that show different result. Below is...

Hi, I'm doing a project about dilated kidneys, these can be arranged into mild, moderate and severe. There are 53 patients in total. I want to see if there is a trend in the severity of dilatation between those that have an 'adverse outcome' (like surgery, scarring etc) and those who do not...

We are working on a project were the sex of sticklebacks in perch stomachs are assesed. The question here is; how do we avoid pseudoreplication? We want to find out if there is a difference in consumption of the different sexes AND we want to find out if the ratio differs from the sex-ratio...

Dear TalkStat Forum members, I was hoping to get some advice over whether I am using the appropriate test for data that I have. The notes of 70 patients were analysed and 2 variables (documentation of postive symptoms yes/no and negative symptoms yes/no) were noted on 4 occasions. An...

I work for a community group restoring beaches. We've done some preliminary investigation of the vegetation along a shoreline to compare against regional mapping. I have a basic knowledge of statistics but could use some help. 10x100m of shoreline have been sampled to determine dominant...

Hi there, I'm trying to teach myself statistics from a book but I don't understand when I have to use t test and when chi squares. I tried to look it up on google but I still don't get it! To what I understood, you use BOTH for determining if there's a difference between groups and if this...

Hi all, I was wondering - what's the relationship between chi square and odds ratio? To me it makes sense that these two values are fixed- i.e., if one value changes, the other will. Is it possible to observe the same odds ratio in two different tests with different sample sizes but get a...

Hello, I have an ordinal variable which assumes only 3 values. I need to do a comparison between 2 treatments. I used Mann-Whitney test, since is an ordinal. My "p-value" is quite high (0.9388) which is strange because the values distribution is quite different for each group. Then I...

Let X1 and X2 be two independent random variables. Let X1 and Y = X1 + X2 be χ2(r1) (Chi Square) and χ2(r), respectively, where r1 < r. (a) Find the mgf of X2. (b) What is its distribution?

Okay...I have calculated my chi square with an answer of 8.33. No alpha is specified (so Im assuming it would be stated as 0.05). Degrees of freedom is 1 Question 1: How do I know what the p value is from this information question 2: what does 8.33 mean? does this correspond to a p value...

Hi there If anyone could help me , with what is probably a really simple/stupid question, I would be so grateful! It is not through lack of trying and reading to understand this- but I'm still really confused. I have done a chi square 2x3, the assumptions were met as all expected...

Hi, I'm very much working in stats by necessity, so much of my knowledge is coming somewhat on the fly. I had a question about two non-parametric tests and I wanted to see if I could get some feedback here.... In my field researchers are suggesting the use of Fisher exact test over chi...