diff --git a/README.md b/README.md
index 57aeb9b..7f7cba9 100644
Binary files a/README.md and b/README.md differ
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..e69de29
diff --git a/goodcalc.go b/goodcalc.go
index 83b6fe2..3c62dac 100644
--- a/goodcalc.go
+++ b/goodcalc.go
@@ -9,8 +9,8 @@ package goodcalc
 type Aspect struct {
 	No                 string  `json:"no"`
 	Weight             float32 `json:"weight"`
-	MaxValuationPoints int     `json:"max_valuation_points"`
 	ValuationPoints    int     `json:"valuation_points"`
+	maxValuationPoints int
 }
 
 // NegativeAspect has the same fields like Aspect. But the
diff --git a/matrix.go b/matrix.go
index 5d634e9..d2923a7 100644
--- a/matrix.go
+++ b/matrix.go
@@ -38,6 +38,7 @@ func (m *Matrix) String() string {
 	return s
 }
 
+// BalancePoints calculates the ecogood points for the matrix
 func (m *Matrix) BalancePoints() int {
 	var balancePoints float64
 	m.calcWeightFactor()
@@ -105,13 +106,13 @@ func (m *Matrix) setMaxValuationPoints() {
 	m.forall(func(t *Theme) {
 		maxThemeValPoints := 0
 		for _, a := range t.Aspects {
-			a.MaxValuationPoints = m.MaxValuationPoints * int(a.Weight)
+			a.maxValuationPoints = m.MaxValuationPoints * int(a.Weight)
 			maxThemeValPoints += m.MaxValuationPoints * int(a.Weight)
 		}
 		t.Calc.MaxValuationPoints = maxThemeValPoints
 		for _, na := range t.NegativeAspects {
-			na.MaxValuationPoints = m.MaxNegValuationPoints
+			na.maxValuationPoints = m.MaxNegValuationPoints
 		}
-		t.NegPointsFactor = m.NegPointsFactor
+		t.negPointsFactor = m.NegPointsFactor
 	})
 }
diff --git a/matrix_test.go b/matrix_test.go
index b2de722..3831e09 100644
--- a/matrix_test.go
+++ b/matrix_test.go
@@ -35,7 +35,7 @@ func emptyMatrix() *Matrix {
 				Weight:          1,
 				Aspects:         []Aspect{},
 				NegativeAspects: []NegativeAspect{},
-				NegPointsFactor: 0,
+				negPointsFactor: 0,
 				Calc:            &ThemeCalc{},
 			}
 
diff --git a/theme.go b/theme.go
index ec065f2..f974ad4 100644
--- a/theme.go
+++ b/theme.go
@@ -10,8 +10,8 @@ type Theme struct {
 	Weight          float32          `json:"weight"`
 	Aspects         []Aspect         `json:"aspects"`
 	NegativeAspects []NegativeAspect `json:"negative_aspects"`
-	NegPointsFactor int              `json:"neg_points_factor"`
 	Calc            *ThemeCalc       `json:"calculation"`
+	negPointsFactor int
 }
 
 func (t *Theme) String() string {
@@ -20,7 +20,7 @@ func (t *Theme) String() string {
 	s += fmt.Sprintf("    Weight: %.1f\n", t.Weight)
 	s += fmt.Sprintf("    Aspects: %v\n", t.Aspects)
 	s += fmt.Sprintf("    NegativeAspects: %v\n", t.NegativeAspects)
-	s += fmt.Sprintf("    NegPointsFactor: %v\n", t.NegPointsFactor)
+	s += fmt.Sprintf("    NegPointsFactor: %v\n", t.negPointsFactor)
 	s += fmt.Sprintf("    Calc: %s\n", t.Calc)
 	return s
 }
@@ -52,7 +52,7 @@ func (t *Theme) calcBalancePoints() {
 	t.Calc.BalancePoints =
 		t.Calc.EstPercentage * t.Calc.MaxBalancePoints
 	t.Calc.NegativeBlancePoints =
-		float32(t.Calc.NegativeValuationPoints) * t.Calc.MaxBalancePoints / float32(t.NegPointsFactor)
+		float32(t.Calc.NegativeValuationPoints) * t.Calc.MaxBalancePoints / float32(t.negPointsFactor)
 }
 
 // ThemeCalc contains the different calculation