# BDI and CDI example 2

Subject: Advertising and Public Relations

Exam: TEE

Reader: https://deep-learning-study-room.vercel.app/apr/#tee/practice/numbers/indices2

Canonical: https://deep-learning-study-room.vercel.app/read/apr/tee/practice/numbers--indices2/

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

### Optional practice question. An area contains 20% of the relevant population, accounts for 10% of total brand sales and 30% 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 |
| --- | --- | --- |
| 20% | 10% | 30% |

## 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



$$
\text{BDI}=\frac{10}{20}\times100
$$



#### Step 2. Divide and scale BDI



$$
0.5\times100=50
$$



#### Step 3. Substitute for CDI



$$
\text{CDI}=\frac{30}{20}\times100
$$



#### Step 4. Divide and scale CDI



$$
1.5\times100=150
$$



#### Step 5. Compare each with 100

Category demand is over-represented but the brand is under-represented; investigate a possible brand gap.

**Final answer:** BDI = 50; CDI = 150.

#### Practical interpretation · What the answer means

Category demand is over-represented but the brand is under-represented; investigate a possible brand gap. Indices guide further analysis; they do not guarantee future growth or prescribe an automatic budget decision.