Edexcel S1 Topic Map

1. Coding

1. eXplanatory, response
2. meaning of correlation in context
3. gradient: for every extra 1 in x, you get an extra m in y
4. intercept: when x is zero, y is expected to be c

1. Variance

1. Estimate from Grouped Data

1. n+1 for individual items, just n for grouped data
2. Skew
   1. Formal definition

      Annotations:

      • for positive: o (Q2-Q1) < (Q3-Q2), i.e. right side of box fatter o OR mean > median > mode, i.e. the lump of the mode happens early on, then there's more spread on the positive side o 3(mean - median) / sd
3. Outliers: 1.5xIQR away from quartiles
4. Interpolation

   Annotations:

   • it's basically about how far through the relevant class our wanted figure is.: (how many items into this group) / (frequency of this group) x class width + class lower bound

Annotations:

• Comment on: o averages (whichever is handy) o spread (sd, iqr, range) o skew use proper statistical names for things, not just "average" or "spread"

1. Curve for continuous, "steps" for discrete

1. Expectation and Variation
   1. Expectation Algebra, Var(aX+b), E(aX+b)
2. Cumulative Probability F(x)
3. simultaneous equations, use sum of p = 1

1. Two sketches every time
2. Mapping ("bridge") equation: z=(x-mu)/sd
   1. if mean and sd missing, set up two bridge equations
3. if you have a prob. or a %, do reverse-lookup in tables to get z value

1. Work from the intersections outwards, P(A) means the whole circle
2. Remember the BOX