Edexcel As Mathematics Statistics Summary Notes

Chapter 1 : Data Collection


Population of interested items
- completely
-
whole set + accurate

census-obseres/measures every member of a population -time consuming and It

sample-selection of observations taken from a subset of a population -> + less data to process
-
Sampling units individual units of a population
- -
not large enough to give
Sampling frame-list of sampling units info about small subsets
Samples:
selection +
simple random everyone has = chance of >
easy cheap
-
-
,




sample frame needed , not good for large pop
--
.
sytematic-chosen at regular intervals from ordered list
- quick good for
large pops .,

-
can introduce bias if frame is bias
stratified-sorted into strata then sample of each > +
-
reflects pop Structure , guarantees proportional rep
.
↳ numberinstratum sample x ia
-
must be clear Strata
quota-researcher selects sample that reflects pop's characteristics > +
-
small sample rep., no frame , quick
-
bids, non-responses not recorded

opportunity-sample of people available +fit criteria -
> +
easy cheap
,



unlikely representative
-




Quantitative- numerical values
Qualitative -
non-numerical observations


Continuous
any value in a
given range
-




·


Discrete-specific values




Chapter 2 Measures :
of Location and Spread

Mean-
Ex frequency table
, =
=
,
in
-




.
Q : n.4 -
if whole number , way between data point and one above

-
if not whole , round up and pick this data point

Q3 :
nx3-rules as above

(2)
variance
02
:


-(Se where Sxx = [x _




n




Standard deviation = I variance
G

if data coded using yea
D

j
=
↳ :
mean



Ey
=
↳