# How is the parameter p\_steps evaluated in Morris method?

**URL:** <https://discourse.julialang.org/t/how-is-the-parameter-p-steps-evaluated-in-morris-method/116124>\
**Category:** Modelling & Simulations\
**Created:** [June 23, 2024, 10:54pm UTC](https://discourse.julialang.org/t/how-is-the-parameter-p-steps-evaluated-in-morris-method/116124 "2024-06-23T22:54:01Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Nick1](https://avatars.discourse-cdn.com/v4/letter/n/47e85d/32.png) [@Nick1](https://discourse.julialang.org/u/Nick1)\
**Post date:** [June 23, 2024, 10:54pm UTC](https://discourse.julialang.org/t/how-is-the-parameter-p-steps-evaluated-in-morris-method/116124/1 "2024-06-23T22:54:01Z")

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It is not clear from the tutorial how the p\_steps parameter is evaluated in Morris method. Usually, the parameters that are defined are the total number of trajectories and the number of trajectories with the highest spread.

Thanks!

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**Author:** ![ChrisRackauckas](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chrisrackauckas/32/77_2.png) [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Post date:** [June 24, 2024, 1:46am UTC](https://discourse.julialang.org/t/how-is-the-parameter-p-steps-evaluated-in-morris-method/116124/2 "2024-06-24T01:46:43Z")

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That is the step size through parameter space, i.e. how large of steps it should be exploring during the calculation. It’s a parameter of the Morris method that requires user input.

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**Author:** ![Nick1](https://avatars.discourse-cdn.com/v4/letter/n/47e85d/32.png) [@Nick1](https://discourse.julialang.org/u/Nick1)\
**Post date:** [June 24, 2024, 6:06pm UTC](https://discourse.julialang.org/t/how-is-the-parameter-p-steps-evaluated-in-morris-method/116124/3 "2024-06-24T18:06:35Z")

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It is not clear to me how it requires user input since it runs fine without it, so I was wondering if it is calculated internally or there is a default value assigned

```julia
m = gsa(funcM,Morris(total_num_trajectory=20000,num_trajectory=2000),param_ranges; batch = false);

```

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<div class="post-metadata">

**Author:** ![ChrisRackauckas](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/chrisrackauckas/32/77_2.png) [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)\
**Post date:** [June 26, 2024, 5:03am UTC](https://discourse.julialang.org/t/how-is-the-parameter-p-steps-evaluated-in-morris-method/116124/4 "2024-06-26T05:03:24Z")

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It defaults to 100 evenly spaced points.