# Re: st: incidence rate and confidence intervals

 From moleps <[email protected]> To [email protected] Subject Re: st: incidence rate and confidence intervals Date Sun, 17 Jan 2010 23:34:52 +0100

```After scrutinizing the manuals- this is as close as I get:
gen pop2=population/100000
capt drop mean up lb
gen mean=.
gen up=.
gen lb=.

forval k=1953/2008{

ci cases if year==`k',e(pop2) pois
replace mean=`r(mean)' if year==`k'
replace up=`r(ub)' if year==`k'
replace lb=`r(lb)' if year==`k'
}
sort year
tw (line mean year) (lowess mean year, lw(thick) bw(0.3)) (lowess up year,bw(0.3)) (lowess lb year,bw(0.3)),xlab(1950(10)2010) xlab(,ang(45)) xtit("Year") ytit("Incidence (per 100,000)") legend(lab(1 Iincidence")  lab(2 "Lowess") lab(3 "95% CI Upper bound") lab(4 "95% CI Lower bound")) leg(col(1))

However looking at the graph and CI´s the upper-limit in the ´50s seem to be lower than the lower-limit in the 2000´s, hence contradicting the poisson regression model (both by continuous year and as "dummy-years,ie i.year"  where year is insignificant after correcting for population. I thought overlapping CI-lines signified a significant effect or is there a problem with the ci-calculations??

regards,
//M

On 17. jan. 2010, at 20.11, moleps wrote:

> Dear listers,
> I´ve got the incidence of a disease in a population in the following data format -year,population,cases-
> I´ve created the incidence rate by dividing cases by population and multiplying by 100000.
>
> gen ins=(cases/population)*100000
> poisson cases year population
>
> **no tendency for increasing incidense after correcting for population.
> **however
>
> line ins ye
>
> **shows an increasing trend. But I´d like to add 95% CI lines to corroborate this. Is this at all possible given my dataset??
>
> Regards,
> //M
>
>
>
>
>
>
>     |  year   population   cases|
>         |----------------------------|
>  1. | 1953    2285542         49 |
>  2. | 1954    3075055         44 |
>  3. | 1955    3015476         50 |
>  4. | 1956    3073404         52 |
>  5. | 1957    3407827         94 |
>     |----------------------------|
>  6. | 1958    3404373         78 |
>  7. | 1959    3343568         79 |
>  8. | 1960    3196884         59 |
>  9. | 1961    3372724         80 |
> 10. | 1962    3508295         67 |
>     |----------------------------|
> 11. | 1963    3348748         84 |
> 12. | 1964    3680068         72 |
> 13. | 1965    3594444         85 |
> 14. | 1966    3270933         67 |
> 15. | 1967    3668785         66 |
>     |----------------------------|
> 16. | 1968    3802479        140 |
> 17. | 1969    3758948        115 |
> 18. | 1970    3765404         75 |
> 19. | 1971    3811994        103 |
> 20. | 1972    3595579         86 |
>     |----------------------------|
> 21. | 1973    3846154         98 |
> 22. | 1974    3972990        122 |
> 23. | 1975    3736829        111 |
> 24. | 1976    4017101        109 |
> 25. | 1977    4035202         96 |
>     |----------------------------|
> 26. | 1978    3972186        100 |
> 27. | 1979    4066134        110 |
> 28. | 1980    3813510        111 |
> 29. | 1981    3908085        121 |
> 30. | 1982    4029101        126 |
>     |----------------------------|
> 31. | 1983    4045128        112 |
> 32. | 1984    4134353        126 |
> 33. | 1985    3998700        136 |
> 34. | 1986    3936817         99 |
> 35. | 1987    4100854        126 |
>     |----------------------------|
> 36. | 1988    4198289        111 |
> 37. | 1989    4124119        114 |
> 38. | 1990    4233116        114 |
> 39. | 1991    4175240         97 |
> 40. | 1992    4198459        112 |
>     |----------------------------|
> 41. | 1993    4124798        113 |
> 42. | 1994    3986070         95 |
> 43. | 1995    4348410        109 |
> 44. | 1996    4369957        135 |
> 45. | 1997    4392714        135 |
>     |----------------------------|
> 46. | 1998    4342720        142 |
> 47. | 1999    4445329        157 |
> 48. | 2000    4478497        135 |
> 49. | 2001    4503436        128 |
> 50. | 2002    4450334        144 |
>     |----------------------------|
> 51. | 2003    4552252        144 |
> 52. | 2004    4577457        150 |
> 53. | 2005    4606363        164 |
> 54. | 2006    4567282        152 |
> 55. | 2007    4681134        153 |
>     |----------------------------|
> 56. | 2008    4571227        150 |
>     +----------------------------+
>
>
>
> *
> *   For searches and help try:
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> *   http://www.ats.ucla.edu/stat/stata/

*
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```