The Use of the Individual Parts of the Aptitude Test for Predicting Success of Students

The Iowa State College Aptitude Test is composed of seven parts or sub-tests. These sub-tests have been used in predicting the success of the students during their first quarter in college

Index number of Iowa farm products prices

The present Iowa farm price index has been in use since 1926. It is widely employed as a measure of the general level of Iowa farm prices and appears each month in the price barometer published in Agricultural Economic Facts2. A few years ago Peck3 developed a farm lease, known as the sliding scale lease, in which the rental payments are based on and vary with the changes in the index number. More recently, contracts covering land sales have been devised in which the interest payments and in some cases also the principal payments are based on this farm price index4. The enactment of the Agricultural Adjustment Act, May, 1933, has occasioned much current interest in parity price which is now computed each month for Iowa and also appears in Agricultural Economic Facts. In the computation of a parity price for the state, it is necessary to have an index of Iowa farm prices. These uses to which the index is put illustrate both the growing interest in such an index and the importance of the greatest possible accuracy in its construction

A Statistical Study of Industrial Science Students of the Class of 1926

This study was carried through with three main objectives in view, 1. To find the relationship between the Iowa State College Aptitude Test (as a whole and in parts), the social and memory tests, work done in high school, and work done in college. 2. To determine the percentage of students; (a) who remained in college (b) who were dropped from college either by their own request or by the request of the scholarship committee. 3. To see if it is possible to determine which high school students should be allowed to enter Iowa State College

Disproportionate subclass numbers in tables of multiple classification

Under the stimulus of some of the newer methods of experimentation there is a decided tendency toward the grouping of classes of data into smaller and more homogeneous sub-classes. The weights of swine, for example, may be simultaneously classified according to the sex as well as the litter of the individual animals. Corn yields may be entered in a three-way table by applying the criteria of variety, treatment and soil type. From the resulting tables of multiple classification can be derived information not only of the main effects, such as sex and litter, but also of the interactions between them. Analysis of variance is the most convenient and effective method of reducing such classified data to summary form and testing the significance of the various effects

Balanced incomplete block and lattice square designs for testing yield differences among large numbers of soybean varieties

Two quasi-factorial arrangements which are especially well adapted to the testing of differences between large numbers of varieties are described and treated in detail as to their analysis and value. The arrangements described are balanced incomplete block and lattice square designs. Soybean variety trials are used to illustrate the analysis and the relative precision on soils of varying homogeneity. Although the efficiency factor of these designs, because of the confounding of variety differences with block effects, is lower than that of randomized complete block designs, yet on soil of normal variability the designs permit the elimination of sufficient variability due to soil differences to more than offset this loss. The merits of the lattice square arrangement are demonstrated on extremely heterogeneous soil where use of the design results in a gain in precision of 150 percent over that of randomized complete blocks. An illustration is also presented in which the design on very uniform soil results in a loss of precision of 31.5 percent. The use of these designs is recommended in variety trials involving large numbers of varieties when the trials are conducted on variable soil and when differences between the varieties are relatively small

The analysis of lattice and triple lattice experiments in corn varietal tests I Construction and numerical analysis by Gertrude M. Cox and Robert C. Eckhardt II Mathematical theory by W. G. Cochran

Two incomplete block designs, the lattice and triple lattice, are discussed. Their construction, the field plans, experimental results, the statistical analysis and new features of the mathematical theory are included. The two experiments consist of yield tests of 81 double-crosses of corn. They are used to illustrate a new method of analysis in which the inter-block information is recovered. The analysis is presented in such a way that it can be adopted as the standard method of analyzing lattice and triple lattice experiments. The recovery of inter-block information and the reduction of block size from 81 to 9 plots per block resulted in a notable increase in precision when compared with the randomized complete block designs. The gain was 85 percent for the lattice experiment and 73 percent for the triple lattice experiment

Experimental Design

xiv, 611 p. : ill. ; 22 c