Как вычислить погрешность компонента Timer

Public Class Form1
    Dim a, M(), i, j, j1, w As Integer
    Dim q, q1 As Single
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Timer1.Interval = 1
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Timer1.Start()
        ListBox1.Items.Clear()
        ListBox2.Items.Clear()
        q = 0 : q1 = 0 : w = 0
    End Sub
 
    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        For Me.i = 0 To 2000
            ReDim Preserve M(i)
            a = Now.Millisecond
            M(i) = a
            ListBox1.Items.Add(i & "=" & a)
        Next
        Timer1.Stop()
    End Sub
 
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Try
            For Me.j = 0 To i
                ReDim Preserve M(i)
                If j + 1 = i Then
                    GoTo 1
                End If
                q = Math.Abs(M(j + 1) - M(j))
                If q > 1 And q < 900 Then
                    q1 += q
                    w += 1
                    ListBox2.Items.Add("w=" & w & "  " & M(j + 1) & "-" & M(j) & "=" & q & "  " & "j+1=" & j + 1 & "  " & " j=" & j)
                End If
            Next
1:          q1 = q1 / w
            Label1.Text = q1
            Label2.Text = w
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
    End Sub
End Class

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        i += 1
        ReDim Preserve M(i)
        a = (Now.Ticks - startDate.Ticks) / 10_000
        M(i) = a
        ListBox1.Items.Add(i & "=" & a)
        If i >= 2000 Then Timer1.Stop()
    End Sub

 a = (Now.Ticks - startDate.Ticks) / 10_000