# difference

1. ### What Stats should I do?

I have data looking at the number of different prey species and the number of different predator species that visited a waterhole and I'm categorizing by time, so eg. 3-6am : 5 prey, 2 predator 6-9am: 10 prey, 1 predator ect. I've tried doing a 2 way anova, and chi squared test but I dont...
2. ### Fixed vs. Random Effects

I'm wondering if someone could help me to correctly identify whether certain variables should be considered fixed or random effects. Just as context, I have a dataset of people (with information about them that I know is FIXED). I have a variable indicating to which healthcare practice...
3. ### Comparing whether there is a significant difference between 3 numbers. Help please!!

Hi, So I have lots of participants for whom I have created a score for on three levels. For each participant, I am trying to find out whether there is a significant difference between the three numbers. I was thinking a one way ANOVA but as I'm doing one participant at a time, I'm not if this...
4. ### Assess statistical significance of two PPVs

Assess significance of the difference between two PPVs I recently validated a medical diagnosis in order to compose a study population. To do so, we classified each patient with a diagnosis of interest as probable, possible, or unlikely case, depending on how likely we believed the diagnosis to...
5. ### Likert Survey -- Stat for comparing single items and sub categories

Hello, For my dissertation I am using an existing 50 item Likert survey. I am pretty sure I will use a t-test to determine if there are differences between my two groups for the individual items. What I am not sure about....is the 50 items are divided into 7 subcategories....to determine...
6. ### Time Series - Difference over time

Hello, I'm new in the time series, so I need some help. I have a short time series (5 quarters), with the proportion of a parameter (public transport-user people). I know there are some effects of TS (trend, seasonal, cyclic and random). I would like to testing the (significant) difference...
7. ### Help needed! Comparison of two datasets

Hi guys, I have two datasets, which basically have data concerning the same event, but recorded by different sources. What I need to do is compare the two data sources. The percentage difference between the two sets fluctuates between 0 and 20%. I'm not sure if percentage difference is the...
8. ### Large differences in Pearson vs Spearman

Dear all, My name is Mark and I am currently writing my thesis for a Master in Economics. I examine whether year to year changes in certain industry variables have an effect on the likelihood of CFO termination (0/1 variable). I have six X-variables, that are calculated as the absolute pro...
9. ### When do I use chi square and when a t-test? I just don't get the difference...

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...
10. ### Is there a difference between z-score and effect size?

I just started teaching statistics to myself (I never had it in school but will need it when I start University). I have problems with z-scores and effect size. I think that you use a z-score if you want to know how a score compares to the mean or standard derivation. And you use the effect...
11. ### Seems so simple: differences... and yet but not between groups... Which test to use?

Hi there :) This seems so simple I'm hoping someone can help me! :confused: I've got the mean values for no. effective alleles in 5 different populations of fish. So, 5 rivers, each with a mean value... and I'm trying to give a statistical value as to whether there are significant...
12. ### Correlation Across Time Help?

Hi I'm a bit lost as to how to calculate the correlation between two groups of numbers across time. I'd like to see if one group, taken from the start of the time frame, has a significant difference or similarity to another group, which represents the remainder of the time. This may be a...
13. ### Comparison of two data sets

Hello, I'm trying to compare two normally distributed data sets that have roughly equivalent standard deviations (at most a factor of 2 different). I'm using the T test to determine a statistical difference between these populations but the p value being returned is often on the order of...
14. ### rearranging content in variable

hi, I'm new at working with STATA. Currently, I face the following problem: I have given data that are organized like that: var1 cat1 cat2 1.2 0 1 5 0 1 ... 7 1 0 2.3 1 0 ... ok so I think the logic behind is easy to grasp. Now I want to subtract...
15. ### Statistics & probability: comparison of two binomial proportions

Case #1: x1 = 121, n1 = 160, p1 = 121/160 = 0.75625 Case #2: x2 = 52, n2 = 100, p2 = 52/100 = 0.52 [symbols have usual meanings; 90% confidence interval to be used] Qn: Estimate the difference between the two proportions - show steps clearly, give a one sentence interpretation.
16. ### Percentage Change - Create other metric to show importance of change

Hi, I have a list of countries with 2 columns of count values that I have calculated the percent change between. Similar to the attached. I am interested in creating a metric to draw attention to the largest differences. For instance, GBR shows a change of only 2.6% but the overall...
17. ### Discrepencies between SPSS and SAS

Does anyone know why there are differences in results when performing Kaplan Meier survival analysis tests in SPSS and SAS. The values do not match exactly and the bigger the sample population, the wider this difference becomes. Does anyone know what the difference in algorithms might be?
18. ### Examining leakage/move of cases between two cluster analysis solutions

Hello! I am looking for the right type of analysis for the following issue. I have conducted two different types of cluster analysis on the same sample and variables. Inevitably, some cases have moved from the one cluster to the other. HOW can I observe this differences? Namely, three people...