added firststeps + reorganized website a bit

material/1_mon/firststeps/statistic_functions.jl

@@ -0,0 +1,51 @@
+#---
+
+function rse_sum(x)
+    s = 0
+    for k = eachindex(x)
+        s = s+x[k]
+    end
+    return s
+end
+
+rse_sum(1:36) == 666
+#---
+
+function rse_mean(x)
+    return rse_sum(x) / length(x)
+end
+
+rse_mean(-15:17) == 1
+
+#----
+function rse_std(x)
+   return  sqrt(rse_sum((x.-rse_mean(x)).^2)/(length(x)-1))
+end
+rse_std([1,2,3]) == 1
+
+#----
+function rse_tstat(x;σ = rse_std(x))
+    return rse_mean(x)./ (σ / sqrt(length(x)))
+end
+
+rse_tstat(2:3) == 5
+
+#---
+struct StatResult
+    x::Vector
+    n::Int32
+    std::Float64
+    tvalue::Float64
+end
+length(s::StatResult) = s.n
+StatResult(x) = StatResult(x,length(x))
+
+StatResult(x,n) =  StatResult(x,n,rse_std(x))
+StatResult(x,n,std) = StatResult(x,n,)
+
+
+mystatresult(10,500.) # <1>
+
+function tstat(x) # <2> generate a function returning our new type
+    return mystatresult(length(x),rse_tstat(x))
+end