I'm trying to make an interaction where skill goes down instead of up, at the same rate as it would normally build. Is that possible? I tried adding a negative amount, but that didn't seem to work.

<V n="periodic_stat_change" t="enabled">
<U n="enabled">
<L n="operations">
<V t="statistic_change">
<U n="statistic_change">
<T n="amount">3</T>
<T n="stat">16656<!--motive_Hunger--></T>
</U>
</V>
<V t="statistic_change">
<U n="statistic_change">
<T n="amount">3</T>
<T n="stat">16654<!--motive_Energy--></T>
</U>
</V>
<V t="statistic_change">
<U n="statistic_change">
<T n="amount">4</T>
<T n="stat">16657<!--motive_Hygiene--></T>
</U>
</V>
<V t="statistic_change">
<U n="statistic_change">
<T n="amount">3</T>
<T n="stat">16652<!--motive_Bladder--></T>
</U>
</V>
<V t="statistic_change">
<U n="statistic_change">
<T n="amount">3</T>
<T n="stat">162675<!--motive_PlantSim_Water--></T>
</U>
</V>
<V t="dynamic_skill">
<U n="dynamic_skill">
<U n="skill_loot_data_override">
<E n="effectiveness">StandardPeriodic</E>
<T n="amount">-3</T>
<T n="stat">16699<!--statistic_Skill_AdultMajor_Charisma--></T>
</U>
</U>
</V>
</L>
</U>
</V>