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<br />001403 <br /> <br />II.7 <br /> <br />Estimating missing records <br /> <br />. <br /> <br />Missing records should be estimated only when it is reasoned. that <br />the estimated. data will be of definite advantage. Simple ratio methods <br />of normals ,or averages (based on a common period). or comparison of <br />slopes on double-mass plottings m~ be used for estimating annual or <br />monthly amounts from adjacent stations. The Weather Bureau estimates <br />missing records by the normal-ratio method. and these estimates are <br />included in the monthly totals published in the annual climatological <br />bulletins. . It should be noted. however. that ratio between stations <br />m~ change' from season to season. Missing daily or stom amounts <br />generally are best estimated by constructing isohyetal maps. For <br />shorter intervals the most desirable procedure would be to compare <br />mass curve$ with those of adjacent stations. Hour of measurements <br />should be watched to insure that the records used are comparable. <br /> <br />Statistical analyses <br /> <br />In using precipitation records for statistical analyses the greatest <br />pitfall is !non-consistent records. Accordingly. a check shciuld be niade on <br />the consistenCy of all records prior to such analyses. Inconsistency in <br />a record. tor example. tends to increase the apparent auto or serial <br />correlatio:t!-. <br /> <br />Early published data <br /> <br />Early ,published data. especially those in Bulletin W. include many <br />estimates df monthly and annual precipitation. Certain of these estimates <br />have been S,hown to be in error; depending upon the intended use of the <br />records. adequate checks should be made of these estimates. In tabulating <br />the records in Bulletin W. no effort was made to check their consistency.' <br />For some stations the data actually were composed from two or more sites <br />fairly well separated in distance or in altitude. Footnotes were used to <br />indicate when records were so combined. <br /> <br />. <br /> <br />,-.' '- <br />",c__. ? <br /> <br />