GCSE Statistics

1. Stratified
2. Systematic
   1. Random starting place, every nth person where n is pop / sample
3. Random
   1. Every item has an equal chance
   2. Using random number tables
4. Quota
5. Key words: sampling frame, sampling unit, census, population

Nota:

• tagged    tagged in recapture ---------  =  --------------------------- total               recapture size

1. Suitable questions (open/closed)
2. Pilot surveys

1. Skew
2. Outliers

Nota:

• Remember to comment on the proportions (angle of slice) and the actual numbers (area)

1. Axes
2. Labels
3. Thickness / colour
4. 3D effect

1. Use midpoints when data is grouped

1. Tied ranks
2. Interpreting the result

1. Equation of the line (gradient / intercept)
2. Make predictions
3. Extrapolation

Nota:

• Get the scale factor or multiplier by doing: eventual value / original value

1. Chain-based
2. Base year
3. Weighted

1. Moving averages
2. Trend line
3. Seasonal variations
   1. Mean seasonal variation / seasonal effect
      1. Predict future value

Nota:

• Work from the inside out - remember P(A) is the probability of the whole A circle. Also, remember the box and the number of items outside the circles.

1. Features, percentages
2. QA charts, warning, action limits