# measurement

1. ### How can I evaluate uncertainty of measure starting from recovery data obtained analyzing spiked samples during method validation?

I'm a researcher working in the field of analytical method validation. I'm studying how I can evaluate the uncertainty of measure starting from recovery data obtained analyzing spiked sample. I found in literature an application in which it's evaluated the reproducibility calculating the RMS...
2. ### Aggregate precision of a measurement instrument based on a sample of measurements whose true errors are known

I want to estimate the accuracy and precision of aggregate data from an instrument that measures a variable that fluctuates over time by comparing a sample of its measurements to concurrent measurements made by a reference instrument. For this purpose, assume that the reference instrument...
3. ### Assessing Reliability Between 2 Metrics

I have constructed two alternative metrics for a particular phenomenon, and I am trying see whether they are approximately equal across the dataset (that is, whether they might be reliable "stand ins" for each other in a larger, later regression analysis, or if one is consistently different from...
4. ### Average of standard deviation as repeat accuracy for five measurement series

Hi there, I hope you can help me with the following question. I measured the power input and output of a storage and retrieval vehicle with 1,000 single measuring points. I repeated the measurement five times with the same measure method and same time steps. The result is five measurement series...
5. ### Is this an interval variable?

The variable is called "externalizing behaviours" and it has the numbers 9,7,7,3,11,6,2,6,6,9. I assume that the numbers show the amount of externalizing behaviour because the question says it was an observation. Is this interval/ratio? I think it is interval (rather than ordinal) because 7 is...
6. ### Modelling continuous measurements

In the attachment from a set of notes, a brief description of how we describe a continuous measurement is described. I have a few basic questions regarding this, any assistance would be appreciated: Questions: I think the motivation for defining \DeltaW_n is to define it as the error per...
7. ### estimate a range of measures

Hello everyone, I am a statistics student, I'm studying for a project in my University. I have to analyze the data, I have available the measures in millimeters corrisponding two different types of objects, of course I have already done tests to groups such as t-test, actually these organized...
8. ### Comparing absolute values of difference scores between two groups

I have two groups (A and B) that each completed a different version of an experimental measure (measure A and measure B). Both groups also completed a standard, "gold standard", measure. For the purposes of my study, I am treating the "gold standard" measure as a participant's true score. If I...
9. ### [LISREL] Looking for a guide to understand output and modify measurement models

Hi all, I am hoping someone can help me as I am so close to the end of my dissertation I can taste it! Okay, so my methodologist suggested that I create a Path Analysis model to test the relationships of my data obtained by community college students who were enrolled in online courses. Here...
10. ### What is the “pdm” stat in the “rms” R package?

I am new to the world of Regression in statistics and I have been doing a research in which I am building an ordinal logistic regression model (ORM). In order to fit my ORM model, I am using the 'orm' function of the 'rms' package from R (http://cran.r-project.org/web/packages/rms/rms.pdf)...
11. ### Comparison quantity with mean values and measurement uncertainty

Hi !! I need help in a problem. I measured a quantity Q from the area A of a peak (normally distributed) divide by two factors. The uncertainty of the measure depends on the st.dev of A (σ_A) and on the uncertainties of the two factors, following the propagation rules for the errors At the...
12. ### Repetead Intervention : which is the right test?

Hi everybody, I'm new with this forum, hence sorry for any mistakes. I'm running a protocol with this scenario: ROUND 1: Baseline Data (T0) - Exercise - Data T1 (immediately after) - Data T2 (after 24h) - Data T3 (after 48 h) ROUND 2: After 1 week Data (T5) - Exercise - Data T6...
13. ### How to measure a moderator: 2 independent variables and one moderator (median split)

Hello to everyone, I have some problems with my diploma work and I really need your help. I am trying to measure a moderating effect on my sample. I looked into the literature and I am still unable to find the answer. What ever I came onto is regarding one IV and one moderator. My IVs...
14. ### Calculating scale total score

I have a variable that is measured using 13-item 4-point Liket scale with the exception of one item (yes=1, no=2). How i can calculate the total score for this variable? Many Thanks Rani