# BDI and CDI example 3

Subject: Advertising and Public Relations

Exam: TEE

Reader: https://deep-learning-study-room.vercel.app/apr/#tee/practice/numbers/indices3

Canonical: https://deep-learning-study-room.vercel.app/read/apr/tee/practice/numbers--indices3/

Extra drills; no claim that these exact questions or allocated marks appeared in TEE

### Optional practice question. An area contains 25% of the relevant population, accounts for 40% of total brand sales and 15% of total category sales. Calculate BDI and CDI and interpret them. [3 practice marks]

#### Answer

Authored illustration: these numbers were chosen to explain a faculty-note concept. No matching supplied-data question was found in the 14 recovered APR papers. Standalone calculation drills are optional practice; their marks are author-set.

## Given

| Population share | Brand-sales share | Category-sales share |
| --- | --- | --- |
| 25% | 40% | 15% |

## To find

Brand and category development indices.

## Formula and why



$$
\text{BDI}=\frac{B_{\%}}{P_{\%}}\times100,\qquad\text{CDI}=\frac{C_{\%}}{P_{\%}}\times100
$$



The common denominator is population share. Only the numerator changes between brand sales and category sales.

## Step-by-step solution

#### Step 1. Substitute for BDI



$$
\text{BDI}=\frac{40}{25}\times100
$$



#### Step 2. Divide and scale BDI



$$
1.6\times100=160
$$



#### Step 3. Substitute for CDI



$$
\text{CDI}=\frac{15}{25}\times100
$$



#### Step 4. Divide and scale CDI



$$
0.6\times100=60
$$



#### Step 5. Compare each with 100

The brand is over-represented in a category that is under-represented; examine whether the strong brand position can be maintained economically.

**Final answer:** BDI = 160; CDI = 60.

#### Practical interpretation · What the answer means

The brand is over-represented in a category that is under-represented; examine whether the strong brand position can be maintained economically. Indices guide further analysis; they do not guarantee future growth or prescribe an automatic budget decision.