Hi all

I have a question about calculating population-level estimates of total participants in activities in AHTUS to replicate estimates using ATUS. Using infltwt divided by 365 days I obtain numbers that are relatively plausible but they are below the weighted estimates using ATUS. Why is that the case? See below an example:

Using ATUS:

svyset caseid [pw=wt06]

svy: mean sex if year==2018

Population size estimate = 95,591,791,615, which divided by 365 results in about 262 million people.

Using AHTUS:

svyset ident [pw=infltwt]

svy: mean sex if year==2018

Population size estimate = 63,931,201,658, which divided by 365 results in about 172 million people.

See detailed output below. I’m puzzled by this discrepancy. Shouldn’t the two estimates be the same? Which one is correct?

Thanks!

Pilar

**OUTPUT using ATUS**

. svy: mean sex if year==2018

(running mean on estimation sample)

Survey: Mean estimation

Number of strata = 1 Number of obs = 9,593

Number of PSUs = 9,593 Population size = 95,591,791,615

Design df = 9,592

```
| Linearized
| Mean std. err. [95% conf. interval]
```

-------------±-----------------------------------------------

sex | 1.515828 .0070061 1.502095 1.529562

**OUTPUT using AHTUS**

. svy: mean sex if sample==2018

(running mean on estimation sample)

Survey: Mean estimation

Number of strata = 1 Number of obs = 9,593

Number of PSUs = 9,593 Population size = 63,931,201,658

Design df = 9,592

```
| Linearized
| Mean std. err. [95% conf. interval]
```

-------------±-----------------------------------------------

sex | 1.51914 .0061262 1.507132 1.531149