Option Explicit

Private Function GetColIndex(ByVal headerName As String, ByVal ws As Worksheet) As Long
    Dim lastCol As Long
    lastCol = ws.Cells(1, ws.Columns.Count).End(xlToLeft).Column
    Dim m As Variant
    m = Application.Match(headerName, ws.Range(ws.Cells(1, 1), ws.Cells(1, lastCol)), 0)
    If IsError(m) Then
        GetColIndex = 0
    Else
        GetColIndex = CLng(m)
    End If
End Function

Private Function BuildPresentColArray(ByVal headers As Variant, ByVal ws As Worksheet) As Variant
    Dim tmp() As Long
    ReDim tmp(0 To UBound(headers))
    Dim i As Long, c As Long
    c = 0
    For i = LBound(headers) To UBound(headers)
        Dim colIdx As Long
        colIdx = GetColIndex(CStr(headers(i)), ws)
        If colIdx > 0 Then
            tmp(c) = colIdx
            c = c + 1
        End If
    Next i
    If c = 0 Then
        BuildPresentColArray = Array()
    Else
        Dim outArr() As Long
        ReDim outArr(0 To c - 1)
        For i = 0 To c - 1
            outArr(i) = tmp(i)
        Next i
        BuildPresentColArray = outArr
    End If
End Function

Private Function MeanOfRow(ByVal ws As Worksheet, ByVal rowIndex As Long, ByVal colIndexes As Variant) As Variant
    Dim i As Long
    Dim sumVals As Double
    Dim countVals As Long
    sumVals = 0
    countVals = 0
    If IsArray(colIndexes) Then
        For i = LBound(colIndexes) To UBound(colIndexes)
            Dim v As Variant
            v = ws.Cells(rowIndex, CLng(colIndexes(i))).Value
            If Not IsError(v) Then
                If IsNumeric(v) Then
                    sumVals = sumVals + CDbl(v)
                    countVals = countVals + 1
                End If
            End If
        Next i
    End If
    If countVals = 0 Then
        MeanOfRow = CVErr(xlErrNA)
    Else
        MeanOfRow = sumVals / countVals
    End If
End Function

Private Function EnsureOutputColumn(ByVal ws As Worksheet, ByVal headerName As String) As Long
    Dim c As Long
    c = GetColIndex(headerName, ws)
    If c = 0 Then
        Dim lastCol As Long
        lastCol = ws.Cells(1, ws.Columns.Count).End(xlToLeft).Column
        c = lastCol + 1
        ws.Cells(1, c).Value = headerName
    End If
    EnsureOutputColumn = c
End Function

Sub BS_Means()
    Dim ws As Worksheet
    Set ws = ThisWorkbook.Sheets(1)

    Dim all28 As Variant
    all28 = Array( _
        "lock_T_easy", "hume_F_easy", "papy_T_easy", "sham_T_easy", "list_F_easy", "cons_T_easy", "tsun_T_easy", "pana_T_easy", "kabu_T_easy", "gulf_F_easy", "oedi_T_easy", "vaud_T_easy", "mont_F_easy", "demo_F_easy", _
        "spee_F_hard", "dwar_F_hard", "carb_T_hard", "bohr_T_hard", "gang_F_hard", "vitc_F_hard", "hert_F_hard", "pucc_F_hard", "troy_T_hard", "moza_F_hard", "croc_F_hard", "gees_F_hard", "lute_F_hard", "memo_F_hard" _
    )

    Dim easy14 As Variant
    easy14 = Array( _
        "lock_T_easy", "hume_F_easy", "papy_T_easy", "sham_T_easy", "list_F_easy", "cons_T_easy", "tsun_T_easy", "pana_T_easy", "kabu_T_easy", "gulf_F_easy", "oedi_T_easy", "vaud_T_easy", "mont_F_easy", "demo_F_easy" _
    )

    Dim hard14 As Variant
    hard14 = Array( _
        "spee_F_hard", "dwar_F_hard", "carb_T_hard", "bohr_T_hard", "gang_F_hard", "vitc_F_hard", "hert_F_hard", "pucc_F_hard", "troy_T_hard", "moza_F_hard", "croc_F_hard", "gees_F_hard", "lute_F_hard", "memo_F_hard" _
    )

    Dim colsAll As Variant, colsEasy As Variant, colsHard As Variant
    colsAll = BuildPresentColArray(all28, ws)
    colsEasy = BuildPresentColArray(easy14, ws)
    colsHard = BuildPresentColArray(hard14, ws)

    Dim colBS28 As Long, colBSEasy As Long, colBSHard As Long
    colBS28 = EnsureOutputColumn(ws, "bs_28")
    colBSEasy = EnsureOutputColumn(ws, "bs_easy")
    colBSHard = EnsureOutputColumn(ws, "bs_hard")

    Dim lastRow As Long
    lastRow = ws.Cells(ws.Rows.Count, "A").End(xlUp).Row

    Dim r As Long
    For r = 2 To lastRow
        ws.Cells(r, colBS28).Value = MeanOfRow(ws, r, colsAll)
        ws.Cells(r, colBSEasy).Value = MeanOfRow(ws, r, colsEasy)
        ws.Cells(r, colBSHard).Value = MeanOfRow(ws, r, colsHard)
    Next r
End Sub