Subject: Heating repair—request for confirmed completion date

Dear [Landlord’s Name],

I’m following up on the heating issue I first reported on [date]. It has now been three weeks, and the heating is still not working. This is affecting my ability to live comfortably in the property and needs to be resolved promptly.

Please confirm by [date] when a qualified technician will attend and when the repair is expected to be completed. If there is a delay with parts or scheduling, please let me know what temporary heating arrangements you can provide in the meantime.

I’d like to resolve this cooperatively. My priority is simply to have reliable heating restored, and I’m happy to coordinate access to help get the work done.

Thank you for your prompt attention. I look forward to receiving a confirmed plan.

Kind regards, [Your Name] [Property Address]

import { useEffect, useState } from "react";

/**
 * Returns the value after it has stopped changing for `delayMs`.
 * Cancels pending updates when the value/delay changes or on unmount.
 */
export function useDebouncedValue<T>(value: T, delayMs: number): T {
  const [debouncedValue, setDebouncedValue] = useState<T>(() => value);

  useEffect(() => {
    const timeoutId = setTimeout(() => {
      // The wrapper also supports function-valued T.
      setDebouncedValue(() => value);
    }, delayMs);

    return () => {
      clearTimeout(timeoutId);
    };
  }, [value, delayMs]);

  return debouncedValue;
}

Usage:

import { useState } from "react";
import { useDebouncedValue } from "./useDebouncedValue";

export function SearchInput() {
  const [query, setQuery] = useState("");
  const debouncedQuery = useDebouncedValue(query, 300);

  return (
    <div>
      <input
        value={query}
        onChange={(event) => setQuery(event.target.value)}
        placeholder="Search…"
      />
      <p>Debounced query: {debouncedQuery}</p>
    </div>
  );
}

The initial value is returned immediately. Subsequent changes are delayed until delayMs has elapsed without another change; effect cleanup cancels the pending timer on unmount.

About 33.2%—assuming “99% accurate” means both 99% sensitivity and 99% specificity. That is, the test detects 99% of users and correctly gives a negative result to 99% of non-users.

Imagine testing 20,000 people:

Of the 298 positive results, only 99 are from actual users:

[ P(\text{uses drug}\mid\text{positive})=\frac{99}{99+199}\approx \boxed{33.2\%}. ]

Why it surprises people: We tend to confuse “the test is positive in 99% of users” with “99% of people who test positive are users.” Those are different probabilities. Because non-users vastly outnumber users, even a 1% false-positive rate produces more false positives than true positives. Ignoring this imbalance is called base-rate neglect.

If “99% accurate” refers only to overall accuracy, rather than sensitivity and specificity separately, there isn’t enough information to calculate the answer.