Knox Tests Research Articles

Second‐order preserving point process permutations

While random permutations of point processes are useful for generating counterfactuals in bivariate interaction tests, such permutations require that the underlying intensity be separable. In many real‐world datasets where clustering or inhibition is present, such an assumption does not hold. Here, we introduce a simple combinatorial optimization algorithm that generates second‐order preserving (SOP) point process permutations, for example, permutations of the times of events such that the function of the permuted process matches the function of the data. We apply the algorithm to synthetic data generated by a self‐exciting Hawkes process and a self‐avoiding point process, along with data from Los Angeles on earthquakes and arsons and data from Indianapolis on law enforcement drug seizures and overdoses. In all cases, we are able to generate a diverse sample of permuted point processes where the distribution of the functions closely matches that of the data. We then show how SOP point process permutations can be used in two applications: (1) bivariate Knox tests and (2) data augmentation to improve deep learning‐based space‐time forecasts.

Spatiotemporal clustering of in-hospital Clostridioides difficile infection.

To determine whether Clostridioides difficile infection (CDI) exhibits spatiotemporal interaction and clustering. Retrospective observational study. The University of Iowa Hospitals and Clinics. This study included 1,963 CDI cases, January 2005 through December 2011. We extracted location and time information for each case and ran the Knox, Mantel, and mean and maximum component size tests for time thresholds (T = 7, 14, and 21 days) and distance thresholds (D = 2, 3, 4, and 5 units; 1 unit = 5-6 m). All tests were implemented using Monte Carlo simulations, and random CDI cases were constructed by randomly permuting times of CDI cases 20,000 times. As a counterfactual, we repeated all tests on 790 aspiration pneumonia cases because aspiration pneumonia is a complication without environmental factors. Results from the Knox test and mean component size test rejected the null hypothesis of no spatiotemporal interaction (P < .0001), for all values of T and D. Results from the Mantel test also rejected the hypothesis of no spatiotemporal interaction (P < .0003). The same tests showed no such effects for aspiration pneumonia. Our results from the maximum component size tests showed similar trends, but they were not consistently significant, possibly because CDI outbreaks attributable to the environment were relatively small. Our results clearly show spatiotemporal interaction and clustering among CDI cases and none whatsoever for aspiration pneumonia cases. These results strongly suggest that environmental factors play a role in the onset of some CDI cases. However, our results are not inconsistent with the possibility that many genetically unrelated CDI cases occurred during the study period.

Space-time clustering of childhood cancers in Switzerland: A nationwide study

The aetiology of childhood cancers remains largely unknown. It has been hypothesized that infections may be involved and that mini-epidemics thereof could result in space-time clustering of incident cases. Most previous studies support spatio-temporal clustering for leukaemia, while results for other diagnostic groups remain mixed. Few studies have corrected for uneven regional population shifts which can lead to spurious detection of clustering. We examined whether there is space-time clustering of childhood cancers in Switzerland identifying cases diagnosed at age <16 years between 1985 and 2010 from the Swiss Childhood Cancer Registry. Knox tests were performed on geocoded residence at birth and diagnosis separately for leukaemia, acute lymphoid leukaemia (ALL), lymphomas, tumours of the central nervous system, neuroblastomas and soft tissue sarcomas. We used Baker's Max statistic to correct for multiple testing and randomly sampled time-, sex- and age-matched controls from the resident population to correct for uneven regional population shifts. We observed space-time clustering of childhood leukaemia at birth (Baker's Max p = 0.045) but not at diagnosis (p = 0.98). Clustering was strongest for a spatial lag of <1 km and a temporal lag of <2 years (Observed/expected close pairs: 124/98; p Knox test = 0.003). A similar clustering pattern was observed for ALL though overall evidence was weaker (Baker's Max p = 0.13). Little evidence of clustering was found for other diagnostic groups (p > 0.2). Our study suggests that childhood leukaemia tends to cluster in space-time due to an etiologic factor present in early life.

Spatial and temporal epidemiology of porcine epidemic diarrhea (PED) in the Midwest and Southeast regions of the United States

Emergence of porcine epidemic diarrhea virus (PEDV) in the US in 2013 caused a major impact in the swine industry due to its high mortality and rapid spread through the country. Even though the role of potential sources of infection in the epidemiology of the disease at the farm level (feed, fomites) has been extensively investigated, there is a lack of knowledge about the dynamics of disease spread at the regional level. Here, we investigated the dissemination of PEDV infection in two areas located in the regions with the highest swine density in the country (Southeast and Midwest) including more than 2400 farms. Location and date of outbreaks were used to assess the spatial and temporal clustering of cases using global (Cuzick–Edwards, Knox and directional tests) and local (Bernouilli model of the spatial scan statistic) techniques in the first 10 months of the epidemic. A strong spatio-temporal pattern was detected in both areas of study, with an increased risk of disease at <2km distances of recently (<7 days) infected farms, although extent of clustering was higher in the Southeast. Results, computed for two different locations in the first months of the epidemic, suggest that local transmission from infected farms into neighboring PEDV-free sites is a likely explanation for a substantial proportion of the reported PEDV-positive farms and consistent with the rapid spread of a highly infectious disease in the absence of immunity.

Howard Andrew Knox: Pioneer of Intelligence Testing at Ellis Island by John T. E. Richardson (review)

Reviewed by: Howard Andrew Knox: Pioneer of Intelligence Testing at Ellis Island by John T. E. Richardson Alan M. Kraut John T. E. Richardson . Howard Andrew Knox: Pioneer of Intelligence Testing at Ellis Island. New York: Columbia University Press, 2011. xxxii + 309 pp. Ill. $55.00 (978-0231-14168-0). In the second decade of the twentieth century, during a peak period of immigration to the United States, Dr. Howard Andrew Knox was physician in the U.S. Marine Hospital Service (later renamed the Public Health Service) assigned to the medical inspection of immigrants at New York's Ellis Island depot. He served there for only four years, May 1912 to May 1916. However, Knox's interest in psychology and his concern about the questionable mental capacity of immigrants seeking admission to the United States led him to make a significant contribution to intelligence testing, according to biographer John T. E. Richardson, professor of student learning and assessment at the Open University in the United Kingdom and former psychology professor at Brunel University. Richardson's stated purpose is to recover from obscurity Knox's legacy and to restore his rightful place of importance in the history of intelligence testing. Born in 1885, Knox was raised in Michigan by his mother, the daughter of Irish immigrants, and a stepfather who was a physician. After graduating with a medical degree from Dartmouth, Knox joined the Army Medical Corps. When he resigned his position to care for his ailing, widowed mother, he was refused reinstatement. In the absence of evidence, Richardson speculates that the refusal resulted from Knox's departure from his post for family reasons, Knox's own divorce and rapid remarriage, which suggested to superiors a troubling instability, or the scorn of prudish superiors resulting from Knox's distribution of prophylactic kits to enlisted men and prostitutes to curb rampant venereal disease at Fort Hancock, New Jersey. Knox resumed government service in 1912, successfully passing the rigorous U.S. Marine Hospital Service examination. Assigned to Ellis Island, Knox joined the line inspection of immigrants traveling third class and steerage. Ellis Island medical officers became sharp observers. Based on a brief clinical gaze, they surmised whether the immigrant before them required further examination to confirm a diagnosis of disease or disability that would prevent newcomers from supporting themselves and might even pose a health risk to the American population. Mental deficiency was harder to diagnose. Often a gesture or facial expression provided a clue. But appearances could be deceiving. [End Page 128] In an era when definitions of mental deficiency were protean and terms such as moron and imbecile had clinical meaning, there were no reliable measures of intelligence. Examinations developed in Europe, such as the Binet exam, required language skills and a cultural familiarity beyond most immigrants' capability. Researcher H. H. Goddard's use of the Binet test on Ellis Island produced problematic results, and Ellis Island inspectors trusted their own instincts more than Goddard's data. Intrigued by psychology, Howard Knox developed performance tests requiring language comprehension only for instructions. Knox's Diamond Frame Test required associating the shape of blocks with their places in a board within a certain amount of time. His Cube Imitation Test required tapping other blocks in a particular pattern. An Inkblot Imagination Test called for immigrants to interpret the shape of an inkblot as they perceived it. Knox's articles describing these tests and several others were commercially packaged and marketed with the blessing and cooperation of the U.S. Public Health Service. Later, other distinguished intelligence testers proceeded to develop more sophisticated performance tests and explanations for precisely what such tests measured. Some cited Knox's tests in their scholarly papers; others did not. Knox's contribution fell into obscurity. As distinguished psychologist Robert J. Sternberg observes in a preface, "[P]art of becoming a revered pioneer in a field is a matter of luck, which eluded Knox." After Knox left Ellis Island in 1916, he engaged in an undistinguished private medical practice until his death in 1949. Richardson makes the case for Knox's contribution to intelligence testing. Less apparent is whether its significance warrants a biography rather than a lengthy article...

Population shift bias in tests of space–time interaction

Common to all tests of space–time interaction is the assumption that the population underlying the events of interest exhibits a trajectory of growth that is consistent through time and across space. In practice, however, this assumption is often untenable and, when violated, can introduce population shift bias into the results of these tests. While this problem is widely recognized, more work remains to compare its effect across tests and to determine the extent to which it is a problem for study short periods. This paper quantifies and compares the population shift bias present in the results of the Knox, Mantel, and Jacquez tests of space–time interaction. A simulation study is carried out which quantifies the bias present in each test across a variety of population movement scenarios. Results show a positive relationship between population shift bias and the heterogeneity in population growth across all the tests. They also demonstrate variability in the size of the bias across the three tests for space–time interaction considered. Finally, the results illustrate that population shift bias can be a serious problem for short study periods. Collectively, these findings suggest that an unbiased approach to assessing the significance of space–time interaction test results is needed whenever spatially heterogeneous population change is identified within a study area.

Clustering of cases of type 1 diabetes in high socioeconomic communes in Santiago de Chile: spatio-temporal and geographical analysis

The objective of this study was to describe spatial and space-time patterns of type 1 diabetes in children less than 15 years old, diagnosed between 2000 and 2005 with residence in the Metropolitan Region of Chile. Knox and Mantel tests were used to detect space-time interaction between cases. An ecological Bayesian model adjusted by socioeconomic factor and year was proposed to estimate the incidence by communes. Initially, there was no space-time interaction between cases, but there is evidence of clustering effect in urban areas of the region. The incidence rate for the overall study period was estimated by 6.18/100,000 (95% CI: 5.69-6.70), with a significant annual trend of 8.2% (P < 0.01). The geographical incidence could be explained by the human development index, as a socioeconomic factor. These results suggest that children living in communes with higher socioeconomic levels may be at higher risk of developing type 1 diabetes. Our findings support the hypothesis of an aetiological role of environmental factors in the onset of type 1 diabetes.

Contribution of Imitative Suicide to the Suicide Rate in Prisons

Suicide rates in prisons are high. Our aim was to investigate the contribution of imitative suicide to the prison suicide rate. We used Knox tests for space-time clustering in a case register of natural and self-inflicted deaths in prisons in England and Wales and model simulations to estimate the effect size. We found significant space-time clustering among 657 self-inflicted deaths in 90 prisons over 10 years but no space-time clustering among 430 deaths from natural causes in 87 prisons over this period. Model simulations with an imitation rate of 5.8% (CI 1%-11%) reproduced the observed space-time clustering.

Space-Time Clustering Analyses of Trisomies 13, 18, and 21

ISEE-183 Background: Although maternal age is an established risk factor for trisomy 21, the overall etiology and the relative contribution of genetic and environmental factors toward their prevalence remain unclear. Objective: To use high-quality fully population-based data from a geographically defined region of Northern England with low levels of in or out migration (population 2.6 million, average number of births per year 30,000, 2 main conurbations and extended rural areas) to analyze space-time clustering among cases of trisomy 13, 18, and 21 to inform the debate about their etiology. Material and Methods: The database recorded information on all pregnancy outcomes including terminations. We analyzed all cases diagnosed with trisomy 13, 18, and 21 born during the period 1985 to 2003. Both Knox and K-function tests for space-time interactions between cases were applied with fixed thresholds of close in space and close in time. The locations were taken to be the residential addresses at the time of birth. Tests were repeated using nearest neighbor thresholds to adjust for variation in population density. Results: We analyzed 124 cases of trisomy 13, 260 cases of trisomy 18, and 1151 cases of trisomy 21. There was statistically significant (P < 0.05) space-time clustering for cases of trisomy 21, but not for trisomy 13 or 18. Furthermore, there was significant space-time clustering involving cases of trisomy 21 from more densely populated areas. Conclusions: The highly novel finding of space-time clustering for trisomy 21 is suggestive of a role of environmental factors in their etiology. Future studies should investigate candidate agents such as infections in more detail.

Space–Time Clustering of Glioma Cannot be Attributed to Specific Histological Subgroups

We previously showed that infectious exposures may be involved in the aetiology of adult glioma, by analysing for space-time clustering using population-based data from the South of the Netherlands. Here we extended these analyses and describe in detail the space-time clustering patterns in glioma subgroups, gender and age-categories. Knox tests for space-time interactions between cases were applied with fixed thresholds of close in space, <5 km, and close in time, <1 year apart. We used the spatial coordinates of the addresses at diagnosis in the analyses. Tests were repeated replacing geographical distance with distance to the Nth nearest neighbour. N was chosen such that the mean distance was 5 km. Data were also analysed by a second order procedure based on K-functions. There was only statistically significant space-time clustering for oligodendroglioma. Clustering was present for adults aged 30-54 years and was more pronounced among males. Given the low prior probability of an infectious aetiology for this specific subgroup, these results should probably be interpreted as false-positive. We conclude that space-time clustering of glioma cannot be attributed to a specific glioma subgroup. The observed clustering in our previous study is therefore probably an overall effect within and between glioma subgroups.

Space–time clustering patterns of gliomas in the Netherlands suggest an infectious aetiology

To test the hypothesis that infectious exposures may be involved in glioma aetiology, we have analysed space–time clustering and seasonal variation using population-based data from the South of the Netherlands between 1983 and 2001. Knox tests for space–time interactions between cases were applied, with spatial coordinates of the addresses at time of diagnosis, and with distance to the Nth nearest neighbour. Data were also analysed by a second order procedure based on K-functions. Tests for heterogeneity and Edwards’ test for sinusoidal variation were applied to examine seasonal variation of incidence. There was statistically significant space–time clustering in the Eastern, but not in the Western part of the region. Clustering was only present in adults, particularly in less densely populated areas. There was no evidence for seasonal variation. The results support a role for infectious exposures in glioma aetiology that may act preferentially in certain geographical areas.

Spatial and temporal analysis of the distribution of hantavirus pulmonary syndrome in Buenos Aires Province, and its relation to rodent distribution, agricultural and demographic variables.

We studied the spatial and temporal distribution of Hantavirus Pulmonary Syndrome (HPS) cases from 1998 to 2001 in the Buenos Aires Province, Argentina. HPS is a severe viral disease whose natural reservoir are rodents of the subfamily Sigmodontinae (Muridae) and which occurs in many countries of South and North America. We considered two spatial arrangements: cells of 18.5 x 18.5 km(2); and departments, the political subdivisions of the province, as spatial units. We tested the departure from a Poisson distribution of the number of cases per cell and per month with the Variance/Mean index, while the interaction between spatial and temporal clustering was tested by means of the Knox and Mantel tests. We constructed probability maps in which the HPS rates per department were considered Poisson variates according to population, area and the product of population and area. We analysed the relation between rodent distribution, environmental and demographic variables and HPS cases conducting preliminary univariate analysis from which we selected variables to enter in general linearized models. We found that both the spatial and temporal distribution of cases is strongly aggregated. The spatiotemporal interaction appears to be related to a strong seasonality and the existence of particular ecological conditions rather than epidemic transmission of the disease. The main explanatory variables for the distribution of HPS cases among the departments of the Buenos Aires Province were human population, the distribution of the rodent Oxymycterus rufus and evapotranspiration. The last two variables are probably indicators of favourable ecological conditions for the reservoirs, which encompass other variables not taken into account in this study.

Space-time clustering patterns in childhood solid tumours other than central nervous system tumours.

The aetiology of most childhood solid tumours (other than central nervous system [CNS] tumours) is unclear. To investigate whether certain environmental exposures may be involved, we have analysed for space-time clustering using population-based data from North West England for the period 1954-98. Knox tests for space-time interactions between cases were applied with fixed thresholds of close in space, <5 km, and close in time, <1 year apart. Addresses at birth and at diagnosis were used. Tests were repeated replacing geographical distance with distance to the Nth nearest neighbour. N was chosen such that the mean distance was 5 km. Data were also examined by a second order procedure based on K-functions. There was significant evidence of space-time clustering for Wilms' tumours (p = 0.03 and 0.04, using the geographical distance and nearest neighbour versions of the Knox test; and p = 0.07 and 0.03, using the geographical distance and nearest neighbour versions of the K-function method), and soft tissue sarcomas (p = 0.01, using both the geographical distance and nearest neighbour versions of the Knox test; and p = 0.001 and 0.002, using the geographical distance and nearest neighbour versions of the K-function method) based on time and location at birth, but not time and location at diagnosis. There was little or no evidence of space-time clustering amongst other diagnostic groups. These are the first results to demonstrate space-time clustering for childhood Wilms' tumours and soft tissue sarcomas. The results are consistent with environmental exposure hypotheses, relating to locations pre-natally or peri-natally.

An infectious aetiology for childhood brain tumours? Evidence from space-time clustering and seasonality analyses.

To investigate whether infections or other environmental exposures may be involved in the aetiology of childhood central nervous system tumours, we have analysed for space–time clustering and seasonality using population-based data from the North West of England for the period 1954 to 1998. Knox tests for space–time interactions between cases were applied with fixed thresholds of close in space, <5 km, and close in time, <1 year apart. Addresses at birth and diagnosis were used. Tests were repeated replacing geographical distance with distance to the Nth nearest neighbour. N was chosen such that the mean distance was 5 km. Data were also examined by a second order procedure based on K-functions. Tests for heterogeneity and Edwards' test for sinusoidal variation were applied to examine changes of incidence with month of birth or diagnosis. There was strong evidence of space–time clustering, particularly involving cases of astrocytoma and ependymoma. Analyses of seasonal variation showed excesses of cases born in the late Autumn or Winter. Results are consistent with a role for infections in a proportion of cases from these diagnostic groups. Further studies are needed to identify putative infectious agents.British Journal of Cancer (2002) 86, 1070–1077. DOI: 10.1038/sj/bjc/6600228 www.bjcancer.com© 2002 Cancer Research UK

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Previous studies of space–time clustering in childhood leukaemia have produced equivocal and inconsistent results. To address this issue we have used Manchester Children's Tumour Registry leukaemia data in space–time clustering analyses. Knox tests for space–time interactions between cases were applied with fixed thresholds of close in space, < 5 km and close in time < 1 year apart. Addresses at birth as well as diagnosis were utilized. Tests were repeated replacing geographical distance with distance to the Nth nearest neighbour. N was chosen such that the mean distance was 5 km. Data were also examined by a second order procedure based on K-functions. All methods showed highly significant evidence of space–time clustering based on place of birth and time of diagnosis, particularly for all leukaemias aged 0–14 and 0–4 years, and acute lymphoblastic leukaemia (ALL) 0–4 years. Some results based on location at diagnosis were significant but mainly gave larger P -values. The results are consistent with an infectious hypothesis. Furthermore, we found an excess of male cases over females involved in space–time pairs. We suggest this may be related to genetic differences in susceptibility to infection between males and females. These findings provide the basis for future studies to identify possible infectious agents. © 2000 Cancer Research Campaign

Evaluation of temporal and spatial clustering of horses with Corynebacterium pseudotuberculosis infection

Abstract Objective To determine whether horses with Corynebacterium pseudotuberculosis infections that were examined at a veterinary medical teaching hospital between July 1, 1992, and June 30, 1994 had patterns of temporal or spatial clustering. Animals 134 case and 800 control horses randomly selected from all non-case horses admitted during the study period. Procedures Admission date and geographic location were determined. Scan, Cuzick &amp; Edwards’, and Knox tests were applied to determine whether case horses had patterns of temporal or spatial clustering. Results For all windows ≥ 3 days (134 case horses) and ≥ 7 days (subset of 69 case horses), results of the Scan test were significant. Results of Cuzick &amp; Edwards’ test were significant for all data sets. A significant spatial cluster of case horses was observed for October, November, and December 1992. Results of the Knox test were significant for temporal intervals between 7 and 56 days and spatial intervals between 4.3 and 6.5 km. Higher Knox(x) proportions were observed for temporal intervals of 0 to 7, 8 to 14, 22 to 28, and 29 to 35 days. Conclusions Significant spatial and temporal clustering of horses with C pseudotuberculosis infection was detected. Clinical Relevance Analysis of the results strongly indicates that this disease is directly or indirectly (ie, short distance and time) transmitted. In addition, data analyses indicated an incubation period of 3 to 4 weeks. The disease could be transmitted through horse-to-horse contact or from infected to susceptible horses via insects, other vectors, or contaminated soil. (Am J Vet Res 1999;60:284–291)

Exploratory space-time analysis of reported dengue cases during an outbreak in Florida, Puerto Rico, 1991-1992.

The spatial and temporal distributions of dengue cases reported during a 1991-1992 outbreak in Florida, Puerto Rico (population = 8,689), were studied by using a Geographic Information System. A total of 377 dengue cases were identified from a laboratory-based dengue surveillance system and georeferenced by their residential addresses on digital zoning and U.S. Geological Survey topographic maps. Weekly case maps were generated for the period between June and December 1991, when 94.2% of the dengue cases were reported. The temporal evolution of the epidemic was rapid, affecting a wide geographic area within seven weeks of the first reported cases of the season. Dengue cases were reported in 217 houses; of these 56 (25.8%) had between two and six reported cases. K-function analysis was used to characterize the spatial clustering patterns for all reported dengue cases (laboratory-positive and indeterminate) and laboratory-positive cases alone, while the Barton and David and Knox tests were used to characterize spatio-temporal attributes of dengue cases reported during the 1991-1992 outbreak. For both sets of data significant case clustering was identified within individual households over short periods of time (three days or less), but in general, the cases had spatial pattern characteristics much like the population pattern as a whole. The rapid temporal and spatial progress of the disease within the community suggests that control measures should be applied to the entire municipality, rather than to the areas immediately surrounding houses of reported cases. The potential for incorporating Geographic Information System technologies into a dengue surveillance system and the limitations of using surveillance data for spatial studies are discussed.

A k nearest neighbour test for space-time interaction.

This paper describes a k nearest neighbour statistic sensitive to the pattern of cases expected of space-time clusters of health events. The Knox and Mantel tests are frequently used for space-time clustering but have two disadvantages. First, the selection of critical space-time distances for the Knox test and of a data transformation for the Mantel test is subjective. Second, the Mantel statistic is the sum of the products of space and time distances, is linear in form, and is not sensitive to non-linear associations between small space and time distances expected of contagious processes. The k nearest neighbour statistic is the number of case pairs that are k nearest neighbours in both space and time, and is evaluated under the null hypothesis of independent space and time nearest neighbour relationships. The test was applied to simulated and real data and compared to the Knox and Mantel tests using statistical power comparisons. The k nearest neighbour test proved sensitive to the space-time interaction pattern expected of disease clusters, does not require parameters (such as critical distances) to be estimated from the data, and may be used to test hypotheses about the spatial and temporal scale of the cluster process. The method addresses significant weaknesses in existing space-time cluster tests and should prove useful in the quantification and evaluation of clusters of human health events. Additional research is needed to further document the power of the test under different cluster processes.

Developments in East-Central States in 1974

Total oil production in Illinois, Indiana, Kentucky, and Tennessee in 1974 was 41 million bbl, down 8.9% from 1973. Tennessee had a 275% increase; all the other states had decreases. Gas production in Kentucky was 69.7 Bcf, about the same as in 1973. Gas production in the other states is not significant. A total of 1,964 oil and gas tests was drilled in 1974, up 28.9% from 1973. Exploratory tests totaled 658, up 16.5%; of these, 125 (19%) were successful. Tennessee had 135 oil and gas tests in 1974, up 37.7% from 1973. Exploratory tests were up 28.8%. Total footage drilled was 214,877, of which 140,343 ft was exploratory. Most of the drilling was in Morgan, Scott, and Fentress Counties, where the primary objective was the Lower Mississippian Ft. Payne carbonate rock. Successful exploratory wells in 1974 included 10 new fields, 4 new-pool wildcat discoveries, 1 deeper pool discovery, and 13 extensions. Indian Creek field in Morgan County was the most significant discovery in 1974. Almost all production from this field is from the Ft. Payne; primary reserves are estimated at more than 1 million bbl. Two deep tests, a 6,334-ft basement test in DeKalb County, and a 3,995-ft test in the Copper Ridge Dolomite in Smith County, were drilled in 1974; both were unsuccessful. Several majors reportedly are leasing large blocks in eastern Tennessee. Leasing also continued in the area of Morgan, Scott, and Fentress Counties. Crude oil production in Tennessee in 1974 was 768,700 bbl, up from 205,000 bbl in 1973. Illinois had 795 oil and gas tests in 1974, up 43% from 1973. Exploratory tests were up 12.8%. Total footage drilled in oil and gas tests and service wells was 2,023,761, up 39.9%. Six new fields, 16 extensions, 3 new-pool wildcats, 5 deeper oil pools, and 2 shallower oil pools were discovered. None of the discoveries adds significantly to reserves. About 75% of the 103 new-field wildcat tests drilled were on the shelf area west and northwest of the deep Fairfield basin. Sixty-five of the new-field wildcats tested Devonian or deeper strata. One of the outstanding features of 1974 activity was the large number of wells testing the Mississippian Ullin Limestone (Valmeyeran). For example, Clay City Consolidated field, which had only 3 Ullin producers at the end of 1973, had 43 Ullin test in 1974, of which 14 were completed in the Ullin. Indications are strong that several deep tests will be drilled in Illinois in 1975, with Trenton and deeper strata as their objective. Activity south of the Rough Creek lineament is expected to increase in 1975. Crude oil production in Illinois in 1974 was 27,554,000 bbl, a decline of 10.2%. Indiana had 376 exploratory and development tests in 1974, up 57.3% from 1973. Twenty-nine more exploratory wells were drilled in 1974 than in 1973. Successful exploratory percentage increased from 10.1% in 1973 to 14.1% in 1974. With a few exceptions, all of the drilling activity in 1974 was in the Illinois basin part of Indiana. Exploratory successes included 7 new fields, 14 new pools, and 3 extensions. Three of the 1974 discoveries were on structures that exhibit anomalies which suggest buried Silurian reefs. Sizable undrilled blocks exist in the areas of expectable reefs, and continued testing of these areas is assured. Because of higher crude prices, many old fields which had become uneconomic probably will receive remedial action. Some attempts at tertiary recovery also are ant cipated. Estimated crude oil production in 1974 is 4,950,000 bbl, a decline of 6.8%. A total of 658 oil and gas tests was drilled in Kentucky in 1974, up 4.3% from 1973. Of 184 exploratory tests drilled, 44 (23.9%) were successful. The exploratory successes included 7 fields, 25 extensions, 4 deeper pools, and 8 shallower pools. A Cambrian test in Stephens field, Elliott County, was drilled to TD 9,473 ft and completed as a 500 Mcf gas producer in the Ordovician Wells Creek Formation at 4,875 ft. Among unsuccessful deep exploratory tests in 1974 were a Precambrian test drilled to TD 13,035 ft in Big Sandy field, Floyd County; 2 Knox tests a little more than TD 6,000 ft, 1 in Breckinridge County and 1 in Johnson County; and a 7,608-ft Antietam test in Morgan County. The last 3 wells are new-field wildcats. At year-end a scheduled Cambrian test was drilling in Webster C unty, and Texas Gas was scheduled to complete a Grayson County test to a depth in excess of 13,000 ft.

A Note on the Methodology of Knox's Tests of "Time and Space Interaction"

A Note on the Methodology of Knox's Tests of "Time and Space Interaction"