diff --git a/lib/node_modules/@stdlib/stats/base/dists/beta/entropy/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/beta/entropy/lib/main.js
index a63daaf47852..c6189c4c1281 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/beta/entropy/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/beta/entropy/lib/main.js
@@ -20,6 +20,7 @@
 
 // MODULES //
 
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var digamma = require( '@stdlib/math/base/special/digamma' );
 var betaln = require( '@stdlib/math/base/special/betaln' );
 
@@ -63,7 +64,12 @@ var betaln = require( '@stdlib/math/base/special/betaln' );
 */
 function entropy( alpha, beta ) {
 	var out;
-	if ( alpha <= 0.0 || beta <= 0.0 ) {
+	if (
+		isnan( alpha ) ||
+		alpha <= 0.0 ||
+		isnan( beta ) ||
+		beta <= 0.0
+	) {
 		return NaN;
 	}
 	out = betaln( alpha, beta );
diff --git a/lib/node_modules/@stdlib/stats/base/dists/beta/kurtosis/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/beta/kurtosis/lib/main.js
index 817951c702d6..69d7c054f490 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/beta/kurtosis/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/beta/kurtosis/lib/main.js
@@ -18,6 +18,11 @@
 
 'use strict';
 
+// MODULES //
+
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+
+
 // MAIN //
 
 /**
@@ -61,7 +66,12 @@ function kurtosis( alpha, beta ) {
 	var apb;
 	var out;
 
-	if ( alpha <= 0.0 || beta <= 0.0 ) {
+	if (
+		isnan( alpha ) ||
+		alpha <= 0.0 ||
+		isnan( beta ) ||
+		beta <= 0.0
+	) {
 		return NaN;
 	}
 	axb = alpha * beta;
diff --git a/lib/node_modules/@stdlib/stats/base/dists/beta/mean/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/beta/mean/lib/main.js
index e91e3fe0fd78..e876b8a9f30c 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/beta/mean/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/beta/mean/lib/main.js
@@ -18,6 +18,11 @@
 
 'use strict';
 
+// MODULES //
+
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+
+
 // MAIN //
 
 /**
@@ -56,7 +61,12 @@
 * // returns NaN
 */
 function mean( alpha, beta ) {
-	if ( alpha <= 0.0 || beta <= 0.0 ) {
+	if (
+		isnan( alpha ) ||
+		alpha <= 0.0 ||
+		isnan( beta ) ||
+		beta <= 0.0
+	) {
 		return NaN;
 	}
 	return alpha / ( alpha + beta );
diff --git a/lib/node_modules/@stdlib/stats/base/dists/beta/median/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/beta/median/lib/main.js
index 6e53f44e76a9..25a84477e402 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/beta/median/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/beta/median/lib/main.js
@@ -20,6 +20,7 @@
 
 // MODULES //
 
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var betaincinv = require( '@stdlib/math/base/special/betaincinv' );
 
 
@@ -61,7 +62,12 @@ var betaincinv = require( '@stdlib/math/base/special/betaincinv' );
 * // returns NaN
 */
 function median( alpha, beta ) {
-	if ( alpha <= 0.0 || beta <= 0.0 ) {
+	if (
+		isnan( alpha ) ||
+		alpha <= 0.0 ||
+		isnan( beta ) ||
+		beta <= 0.0
+	) {
 		return NaN;
 	}
 	return betaincinv( 0.5, alpha, beta );
diff --git a/lib/node_modules/@stdlib/stats/base/dists/beta/mode/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/beta/mode/lib/main.js
index 234b8aabab65..8dea53b3cffc 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/beta/mode/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/beta/mode/lib/main.js
@@ -18,6 +18,11 @@
 
 'use strict';
 
+// MODULES //
+
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+
+
 // MAIN //
 
 /**
@@ -56,7 +61,12 @@
 * // returns NaN
 */
 function mode( alpha, beta ) {
-	if ( alpha <= 1.0 || beta <= 1.0 ) {
+	if (
+		isnan( alpha ) ||
+		alpha <= 1.0 ||
+		isnan( beta ) ||
+		beta <= 1.0
+	) {
 		return NaN;
 	}
 	return ( alpha-1.0 ) / ( alpha+beta-2.0 );
diff --git a/lib/node_modules/@stdlib/stats/base/dists/beta/skewness/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/beta/skewness/lib/main.js
index 8ee91cf7d727..56756428b2ea 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/beta/skewness/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/beta/skewness/lib/main.js
@@ -20,6 +20,7 @@
 
 // MODULES //
 
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var sqrt = require( '@stdlib/math/base/special/sqrt' );
 
 
@@ -63,7 +64,12 @@ var sqrt = require( '@stdlib/math/base/special/sqrt' );
 function skewness( alpha, beta ) {
 	var out;
 	var ab;
-	if ( alpha <= 0.0 || beta <= 0.0 ) {
+	if (
+		isnan( alpha ) ||
+		alpha <= 0.0 ||
+		isnan( beta ) ||
+		beta <= 0.0
+	) {
 		return NaN;
 	}
 	ab = alpha + beta;
diff --git a/lib/node_modules/@stdlib/stats/base/dists/beta/stdev/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/beta/stdev/lib/main.js
index 1d6261ba1e17..867b2fb21ea8 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/beta/stdev/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/beta/stdev/lib/main.js
@@ -20,6 +20,7 @@
 
 // MODULES //
 
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var sqrt = require( '@stdlib/math/base/special/sqrt' );
 
 
@@ -63,7 +64,12 @@ var sqrt = require( '@stdlib/math/base/special/sqrt' );
 function stdev( alpha, beta ) {
 	var apb;
 	var out;
-	if ( alpha <= 0.0 || beta <= 0.0 ) {
+	if (
+		isnan( alpha ) ||
+		alpha <= 0.0 ||
+		isnan( beta ) ||
+		beta <= 0.0
+	) {
 		return NaN;
 	}
 	apb = alpha + beta;
diff --git a/lib/node_modules/@stdlib/stats/base/dists/beta/variance/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/beta/variance/lib/main.js
index 0206d45c817c..72cc8500f5f1 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/beta/variance/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/beta/variance/lib/main.js
@@ -18,6 +18,11 @@
 
 'use strict';
 
+// MODULES //
+
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+
+
 // MAIN //
 
 /**
@@ -58,7 +63,12 @@
 function variance( alpha, beta ) {
 	var apb;
 	var out;
-	if ( alpha <= 0.0 || beta <= 0.0 ) {
+	if (
+		isnan( alpha ) ||
+		alpha <= 0.0 ||
+		isnan( beta ) ||
+		beta <= 0.0
+	) {
 		return NaN;
 	}
 	apb = alpha + beta;
diff --git a/lib/node_modules/@stdlib/stats/base/dists/betaprime/mean/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/betaprime/mean/lib/main.js
index 7b47b8788360..8b4ca60daad4 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/betaprime/mean/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/betaprime/mean/lib/main.js
@@ -18,6 +18,11 @@
 
 'use strict';
 
+// MODULES //
+
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+
+
 // MAIN //
 
 /**
@@ -60,7 +65,12 @@
 * // returns NaN
 */
 function mean( alpha, beta ) {
-	if ( alpha <= 0.0 || beta <= 1.0 ) {
+	if (
+		isnan( alpha ) ||
+		alpha <= 0.0 ||
+		isnan( beta ) ||
+		beta <= 1.0
+	) {
 		return NaN;
 	}
 	return alpha / ( beta - 1.0 );
diff --git a/lib/node_modules/@stdlib/stats/base/dists/betaprime/mode/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/betaprime/mode/lib/main.js
index df4cbd80ac3c..635f61780012 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/betaprime/mode/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/betaprime/mode/lib/main.js
@@ -18,6 +18,11 @@
 
 'use strict';
 
+// MODULES //
+
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+
+
 // MAIN //
 
 /**
@@ -60,7 +65,12 @@
 * // returns NaN
 */
 function mode( alpha, beta ) {
-	if ( alpha <= 0.0 || beta <= 0.0 ) {
+	if (
+		isnan( alpha ) ||
+		alpha <= 0.0 ||
+		isnan( beta ) ||
+		beta <= 0.0
+	) {
 		return NaN;
 	}
 	if ( alpha < 1.0 ) {
diff --git a/lib/node_modules/@stdlib/stats/base/dists/f/kurtosis/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/f/kurtosis/lib/main.js
index 871ee2e2b8d4..24f2ca02bdfe 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/f/kurtosis/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/f/kurtosis/lib/main.js
@@ -20,6 +20,7 @@
 
 // MODULES //
 
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var pow = require( '@stdlib/math/base/special/pow' );
 
 
@@ -68,7 +69,12 @@ function kurtosis( d1, d2 ) {
 	var denom;
 	var num;
 
-	if ( d1 <= 0.0 || d2 <= 8.0 ) {
+	if (
+		isnan( d1 ) ||
+		d1 <= 0.0 ||
+		isnan( d2 ) ||
+		d2 <= 8.0
+	) {
 		return NaN;
 	}
 	num = ( d1 * ( ( 5.0*d2 ) - 22.0 ) * ( d1+d2-2.0 ) ) +
diff --git a/lib/node_modules/@stdlib/stats/base/dists/f/mode/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/f/mode/lib/main.js
index 7bce40d62de0..c60424538567 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/f/mode/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/f/mode/lib/main.js
@@ -18,6 +18,11 @@
 
 'use strict';
 
+// MODULES //
+
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+
+
 // MAIN //
 
 /**
@@ -56,7 +61,12 @@
 * // returns NaN
 */
 function mode( d1, d2 ) {
-	if ( d1 <= 2.0 || d2 <= 0.0 ) {
+	if (
+		isnan( d1 ) ||
+		d1 <= 2.0 ||
+		isnan( d2 ) ||
+		d2 <= 0.0
+	) {
 		return NaN;
 	}
 	return ( ( d1-2.0 ) / d1 ) * ( d2 / ( d2+2.0 ) );
diff --git a/lib/node_modules/@stdlib/stats/base/dists/f/skewness/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/f/skewness/lib/main.js
index 3891b44d80e4..05b27fbfb6a9 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/f/skewness/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/f/skewness/lib/main.js
@@ -20,6 +20,7 @@
 
 // MODULES //
 
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var sqrt = require( '@stdlib/math/base/special/sqrt' );
 
 
@@ -66,7 +67,12 @@ var sqrt = require( '@stdlib/math/base/special/sqrt' );
 */
 function skewness( d1, d2 ) {
 	var out;
-	if ( d1 <= 0.0 || d2 <= 6.0 ) {
+	if (
+		isnan( d1 ) ||
+		d1 <= 0.0 ||
+		isnan( d2 ) ||
+		d2 <= 6.0
+	) {
 		return NaN;
 	}
 	out = ( ( 2.0*d1 ) + d2 - 2.0 ) * sqrt( 8.0 * ( d2-4.0 ) );
diff --git a/lib/node_modules/@stdlib/stats/base/dists/f/stdev/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/f/stdev/lib/main.js
index a42a9c4abd3a..59a6ffd5f271 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/f/stdev/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/f/stdev/lib/main.js
@@ -20,6 +20,7 @@
 
 // MODULES //
 
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var sqrt = require( '@stdlib/math/base/special/sqrt' );
 var SQRT2 = require( '@stdlib/constants/float64/sqrt-two' );
 
@@ -67,7 +68,12 @@ var SQRT2 = require( '@stdlib/constants/float64/sqrt-two' );
 */
 function stdev( d1, d2 ) {
 	var out;
-	if ( d1 <= 0.0 || d2 <= 4.0 ) {
+	if (
+		isnan( d1 ) ||
+		d1 <= 0.0 ||
+		isnan( d2 ) ||
+		d2 <= 4.0
+	) {
 		return NaN;
 	}
 	out = SQRT2 * ( d2 / ( d2-2.0 ) );
diff --git a/lib/node_modules/@stdlib/stats/base/dists/f/variance/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/f/variance/lib/main.js
index 7aaa47061dd8..5119d8bec357 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/f/variance/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/f/variance/lib/main.js
@@ -20,6 +20,7 @@
 
 // MODULES //
 
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var pow = require( '@stdlib/math/base/special/pow' );
 
 
@@ -66,7 +67,12 @@ var pow = require( '@stdlib/math/base/special/pow' );
 */
 function variance( d1, d2 ) {
 	var out;
-	if ( d1 <= 0.0 || d2 <= 4.0 ) {
+	if (
+		isnan( d1 ) ||
+		d1 <= 0.0 ||
+		isnan( d2 ) ||
+		d2 <= 4.0
+	) {
 		return NaN;
 	}
 	out = 2.0 * d2 * d2 * ( d1 + d2 - 2.0 );
diff --git a/lib/node_modules/@stdlib/stats/base/dists/gamma/entropy/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/gamma/entropy/lib/main.js
index 321f65038ca4..202912b4bb11 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/gamma/entropy/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/gamma/entropy/lib/main.js
@@ -20,6 +20,7 @@
 
 // MODULES //
 
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var digamma = require( '@stdlib/math/base/special/digamma' );
 var gammaln = require( '@stdlib/math/base/special/gammaln' );
 var ln = require( '@stdlib/math/base/special/ln' );
@@ -64,7 +65,12 @@ var ln = require( '@stdlib/math/base/special/ln' );
 */
 function entropy( alpha, beta ) {
 	var out;
-	if ( alpha <= 0.0 || beta <= 0.0 ) {
+	if (
+		isnan( alpha ) ||
+		alpha <= 0.0 ||
+		isnan( beta ) ||
+		beta <= 0.0
+	) {
 		return NaN;
 	}
 	out = alpha - ln( beta );
diff --git a/lib/node_modules/@stdlib/stats/base/dists/gamma/mean/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/gamma/mean/lib/main.js
index 25eb6124aaef..3bc550e9f43b 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/gamma/mean/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/gamma/mean/lib/main.js
@@ -18,6 +18,11 @@
 
 'use strict';
 
+// MODULES //
+
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+
+
 // MAIN //
 
 /**
@@ -56,7 +61,12 @@
 * // returns NaN
 */
 function mean( alpha, beta ) {
-	if ( alpha <= 0.0 || beta <= 0.0 ) {
+	if (
+		isnan( alpha ) ||
+		alpha <= 0.0 ||
+		isnan( beta ) ||
+		beta <= 0.0
+	) {
 		return NaN;
 	}
 	return alpha / beta;
diff --git a/lib/node_modules/@stdlib/stats/base/dists/gamma/mode/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/gamma/mode/lib/main.js
index 03825713a101..b7e5897db072 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/gamma/mode/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/gamma/mode/lib/main.js
@@ -18,6 +18,11 @@
 
 'use strict';
 
+// MODULES //
+
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+
+
 // MAIN //
 
 /**
@@ -60,7 +65,12 @@
 * // returns NaN
 */
 function mode( alpha, beta ) {
-	if ( alpha < 1.0 || beta <= 0.0 ) {
+	if (
+		isnan( alpha ) ||
+		alpha < 1.0 ||
+		isnan( beta ) ||
+		beta <= 0.0
+	) {
 		return NaN;
 	}
 	return ( alpha-1.0 ) / beta;
diff --git a/lib/node_modules/@stdlib/stats/base/dists/gamma/stdev/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/gamma/stdev/lib/main.js
index dda79b62ae75..c6c35cded2fb 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/gamma/stdev/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/gamma/stdev/lib/main.js
@@ -20,6 +20,7 @@
 
 // MODULES //
 
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var sqrt = require( '@stdlib/math/base/special/sqrt' );
 
 
@@ -61,7 +62,12 @@ var sqrt = require( '@stdlib/math/base/special/sqrt' );
 * // returns NaN
 */
 function stdev( alpha, beta ) {
-	if ( alpha <= 0.0 || beta <= 0.0 ) {
+	if (
+		isnan( alpha ) ||
+		alpha <= 0.0 ||
+		isnan( beta ) ||
+		beta <= 0.0
+	) {
 		return NaN;
 	}
 	return sqrt( alpha ) / beta;
diff --git a/lib/node_modules/@stdlib/stats/base/dists/gamma/variance/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/gamma/variance/lib/main.js
index 2d5c0287671c..3afe227408d0 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/gamma/variance/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/gamma/variance/lib/main.js
@@ -18,6 +18,11 @@
 
 'use strict';
 
+// MODULES //
+
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+
+
 // MAIN //
 
 /**
@@ -56,7 +61,12 @@
 * // returns NaN
 */
 function variance( alpha, beta ) {
-	if ( alpha <= 0.0 || beta <= 0.0 ) {
+	if (
+		isnan( alpha ) ||
+		alpha <= 0.0 ||
+		isnan( beta ) ||
+		beta <= 0.0
+	) {
 		return NaN;
 	}
 	return alpha / ( beta*beta );
diff --git a/lib/node_modules/@stdlib/stats/base/dists/invgamma/entropy/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/invgamma/entropy/lib/main.js
index 2351d731187e..de917ea50151 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/invgamma/entropy/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/invgamma/entropy/lib/main.js
@@ -20,6 +20,7 @@
 
 // MODULES //
 
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var digamma = require( '@stdlib/math/base/special/digamma' );
 var gamma = require( '@stdlib/math/base/special/gamma' );
 var ln = require( '@stdlib/math/base/special/ln' );
@@ -64,7 +65,12 @@ var ln = require( '@stdlib/math/base/special/ln' );
 */
 function entropy( alpha, beta ) {
 	var out;
-	if ( alpha <= 0.0 || beta <= 0.0 ) {
+	if (
+		isnan( alpha ) ||
+		alpha <= 0.0 ||
+		isnan( beta ) ||
+		beta <= 0.0
+	) {
 		return NaN;
 	}
 	out = alpha + ln( beta*gamma( alpha ) );
diff --git a/lib/node_modules/@stdlib/stats/base/dists/invgamma/mean/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/invgamma/mean/lib/main.js
index f1abcf2a9657..4001c7d32410 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/invgamma/mean/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/invgamma/mean/lib/main.js
@@ -18,6 +18,11 @@
 
 'use strict';
 
+// MODULES //
+
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+
+
 // MAIN //
 
 /**
@@ -56,7 +61,12 @@
 * // returns NaN
 */
 function mean( alpha, beta ) {
-	if ( alpha <= 1.0 || beta <= 0.0 ) {
+	if (
+		isnan( alpha ) ||
+		alpha <= 1.0 ||
+		isnan( beta ) ||
+		beta <= 0.0
+	) {
 		return NaN;
 	}
 	return beta / ( alpha - 1.0 );
diff --git a/lib/node_modules/@stdlib/stats/base/dists/invgamma/mode/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/invgamma/mode/lib/main.js
index 08074221bd49..0cd4e8441e27 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/invgamma/mode/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/invgamma/mode/lib/main.js
@@ -18,6 +18,11 @@
 
 'use strict';
 
+// MODULES //
+
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
+
+
 // MAIN //
 
 /**
@@ -56,7 +61,12 @@
 * // returns NaN
 */
 function mode( alpha, beta ) {
-	if ( alpha <= 0.0 || beta <= 0.0 ) {
+	if (
+		isnan( alpha ) ||
+		alpha <= 0.0 ||
+		isnan( beta ) ||
+		beta <= 0.0
+	) {
 		return NaN;
 	}
 	return beta / ( alpha + 1.0 );
diff --git a/lib/node_modules/@stdlib/stats/base/dists/invgamma/stdev/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/invgamma/stdev/lib/main.js
index 8df601fe42ec..6d63cc88d3bc 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/invgamma/stdev/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/invgamma/stdev/lib/main.js
@@ -20,6 +20,7 @@
 
 // MODULES //
 
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var sqrt = require( '@stdlib/math/base/special/sqrt' );
 
 
@@ -61,7 +62,12 @@ var sqrt = require( '@stdlib/math/base/special/sqrt' );
 * // returns NaN
 */
 function stdev( alpha, beta ) {
-	if ( alpha <= 2.0 || beta <= 0.0 ) {
+	if (
+		isnan( alpha ) ||
+		alpha <= 2.0 ||
+		isnan( beta ) ||
+		beta <= 0.0
+	) {
 		return NaN;
 	}
 	return beta / ( ( alpha-1.0 ) * sqrt( alpha-2.0 ) );
diff --git a/lib/node_modules/@stdlib/stats/base/dists/invgamma/variance/lib/main.js b/lib/node_modules/@stdlib/stats/base/dists/invgamma/variance/lib/main.js
index a40144d0afec..d9665c01f3a9 100644
--- a/lib/node_modules/@stdlib/stats/base/dists/invgamma/variance/lib/main.js
+++ b/lib/node_modules/@stdlib/stats/base/dists/invgamma/variance/lib/main.js
@@ -20,6 +20,7 @@
 
 // MODULES //
 
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var pow = require( '@stdlib/math/base/special/pow' );
 
 
@@ -61,7 +62,12 @@ var pow = require( '@stdlib/math/base/special/pow' );
 * // returns NaN
 */
 function variance( alpha, beta ) {
-	if ( alpha <= 2.0 || beta <= 0.0 ) {
+	if (
+		isnan( alpha ) ||
+		alpha <= 2.0 ||
+		isnan( beta ) ||
+		beta <= 0.0
+	) {
 		return NaN;
 	}
 	return ( beta*beta ) / ( pow( alpha-1.0, 2.0 ) * ( alpha-2.0 ) );