Geometric and weighted mean, comparative pie charts and capture/recapture method Flashcards Preview

GCSE Statistics > Geometric and weighted mean, comparative pie charts and capture/recapture method > Flashcards

Flashcards in Geometric and weighted mean, comparative pie charts and capture/recapture method Deck (8)
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1
Q

What is the formula for weighted mean?

A

Σ(value x weight) / Σweights

Σwx / Σw

2
Q

What is the formula for geometric mean?

A

n/value1 x value2 x … x valuen

^ nth route

3
Q

When are comparative pie charts used?

A

To compare two sets of data

4
Q

How does the area of comparative pie charts relate to the total frequencies?

A

They must be in the same ratio

5
Q

What is the formula for calculating the missing ratio of a comparative pie chart? (When given the Σfrequencies and another ratio)

A

r2 = r1 x ((2/F2) / (2/F1))

radius 2 = radius 1 x ((square root of Σ frequency 2) / (square root of Σ frequency 1))

6
Q

When is the Petersen capture-recapture method used?

A

To estimate the size of a population, where it would be impossible to capture all the animals within the population to count

7
Q

What is the Petersen capture-recapture formula?

A

m/n = M/N

N = Mn/m

m = no. marked in second sample

n = no. caught in second sample

M = no. given tags in first sample

N = total population

8
Q

What assumptions are made for the Petersen capture-recapture method?

A

The population hasn’t changed - no members have entered or left, and there have been no births or deaths

The probability of being caught is equal for all individuals

Marks/tags are not lost and are always recognisable

The sample size is big enough to be representative of the population