Please help me critique my statistical design of my experiment

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Discussion Overview

The discussion revolves around the statistical design of an experiment investigating the effects of a knockout gene on learning and memory in mice, specifically using the Morris water maze as a testing method. Participants are addressing issues related to statistical analysis, including the use of standard error versus confidence intervals, variability among subjects, and potential additional analyses.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • The original poster (OP) seeks clarification on the difference between standard error and confidence intervals, questioning whether standard error is traditionally one standard deviation and if changing the CI parameter from 0.95 to 0.66 would be appropriate for standard error.
  • The OP expresses interest in analyzing variability within the knockout strain, suggesting that some mice may be more affected than others, and asks for recommendations on statistical tests to explore this variability.
  • The OP also wants to investigate the rate and degree of change in learning between strains, inquiring about suitable statistical tests for this analysis.
  • One participant advises consulting published literature to understand how others have approached similar experiments, questioning the validity of swim speed as an indicator of memory and suggesting that simulation could be a valuable analytical tool.
  • Another participant emphasizes that while swim speed may not directly measure memory, it could relate to learning, and discusses the distinction between elapsed time and speed in the context of measuring spatial intelligence.
  • A later reply mentions that swim speed could indicate Alzheimer's-like activity, providing a rationale for its use in the experiment.

Areas of Agreement / Disagreement

Participants express differing views on the appropriateness of swim speed as a measure of memory and learning, with some questioning its validity while others suggest it may have relevance. The discussion remains unresolved regarding the best statistical approaches and the interpretation of swim speed in the context of the experiment.

Contextual Notes

There are unresolved assumptions regarding the definitions of standard error and confidence intervals, as well as the implications of using swim speed as a measure of learning and memory. The OP's inquiries about statistical tests indicate a need for clarity on the appropriate methodologies for their specific experimental design.

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Hello all,

I am currently doing statistical analysis of a knockout vs control mouse strain, investigating a gene that codes a protein that is hypothesized to be involved in learning and memory.

To do the test, we ran mice in a morris water maze, which involves placing mice in a little pool, the water is made opaque with milk, and a platform that they can stand on is hidden just under the water. Markers are placed at the four cardinal directions, in the form of a star, circle, triangle, and square, so that ideally, the mouse will learn where the platform is after being placed in the pool a few times, and swim there immediately (because like many mammals, they can swim, though they prefer not to)

I am measuring two dependent variables, swim speed and path length. We put the mice in 7 days and measure their progress. I made two figures using Statistica, which were made using ANOVA, which broke them down into strains and had the timepoints (x axis) as days, and y-axis as pathlength, and the next figure was the same except y-axis was swimspeed.

FIRST PROBLEM:

Statistica allows you to select adding 'standard error', which puts up vertical bars on the time points which correspond to Confidence Interval of 95%. My boss said he wants standard error instead of confidence interval. I was wondering what the difference is. Is standard error traditionally 1 standard deviation while the confidence interval I selected was roughly equal to 2? If I want to change the CI to SE, should I change the CI parameter from .95 to about .66?

SECOND PROBLEM:

I want to check out a few more possibilities, like perhaps there is greater variability within particular mice of a particular strain. As in, perhaps the knockout strain is affected unevenly, and *some* mice are very strongly affected, while others not, what statistical tests would you do this with?

Another thing I want to analyze is the rate of change perhaps, and the degree of change. Perhaps these parameters are different in the different strains, maybe the knockouts learn less quickly even though they might have similar means on the initial days, or vice versa. Any ideas on what statistical tests to do this with?

THIRD PROBLEM:

This one is not a big deal, I already truly truly appreciate your help if you have read up to this point, this one is just if you have any ideas for other analyses that might be of interest, feel free to suggest some, but like I said, that's more my job so please don't feel obligated to help me here (of course you are not obligated to help me *at all*, but you know what I mean I hope).

Thanks again
 
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The most obvious advice is consult published papers by other experimenters who used this test and see what they did!

I don't know that literature and I don't understand why swim speed is a good indicator of memory. A mouse could swim fast in the wrong direction, couldn't it? Also, are mice like some humans in that they cannot keep their nose out of the water unless they maintain a certain velocity?

In my opinion, simulation is a valuable tool for analyzing problems. Of course that requires that you have the services of a good computer programmer or have a software package that can do simulation.
 
Stephen Tashi said:
The most obvious advice is consult published papers by other experimenters who used this test and see what they did!

I don't know that literature and I don't understand why swim speed is a good indicator of memory. A mouse could swim fast in the wrong direction, couldn't it? Also, are mice like some humans in that they cannot keep their nose out of the water unless they maintain a certain velocity?

In my opinion, simulation is a valuable tool for analyzing problems. Of course that requires that you have the services of a good computer programmer or have a software package that can do simulation.

Maybe not memory exclusively or specifically, but definitely learning.

When measuring spatial intelligence, one way is to see how long it takes for the test subject to navigate a maze.
 
chiro said:
When measuring spatial intelligence, one way is to see how long it takes for the test subject to navigate a maze.

But "how long" (= elapsed time) is not the same as "speed" by the usual definition of speed.
 
Sorry I didn't elaborate (and I don't have much time atm but I'll give you a quick explanation). One of the reasons 'swim speed' is used, is because that can actually be an indicator of Alzheimer's like activity.
 

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