Beta Indicator

[dscrockett]

This indicator in TOS calls for 2-values - Length and Return Length. Thus, in my mind, the Length equals 252; Return Length equals 30.
If correct, the 252 represents the number of bars during the period; 30 represents the number of bars as a moving average? Can anyone offer an alternative format since the TOS notes give little help? Lastly, the scan study in TOS rarely matches the chart results, offering furth befuddlement. Anyone?

#
# Charles Schwab & Co. (c) 2007-2025
#

declare lower;

input length = 21;
input returnLength = 1;
input index = {Default SPX, "Nasdaq Composite", NDX, Dow30, "Russell 2000"};

assert(returnLength > 0, "'return length' must be positive: " + returnLength);

def primary = if close[returnLength] == 0 then 0 else (close - close[returnLength]) / close[returnLength] * 100;

def logic;
switch(index) {
case SPX:
 logic = close("SPX");
case "Nasdaq Composite":
 logic = close("$COMP");
case NDX:
 logic = close("NDX");
case "Dow30":
 logic = close("$DJI");
case "Russell 2000":
 logic = close("RUT");
}

def secondary = if logic[returnLength] == 0 then 0 else (logic - logic[returnLength]) / logic[returnLength] * 100;

plot Beta = covariance(primary, secondary, length) / Sqr(stdev(secondary, length));
Beta.SetDefaultColor(GetColor(9));