Foldover Technique Research Articles

Cross-Entropy Loss for Recommending Efficient Fold-Over Technique

Due to the limited resources and budgets in many real-life projects, it is unaffordable to use full factorial experimental designs and thus fractional factorial (FF) designs are used instead. The aliasing of factorial effects is the price we pay for using FF designs and thus some significant effects cannot be estimated. Therefore, some additional observations (runs) are needed to break the linages among the factorial effects. Folding over the initial FF designs is one of the significant approaches for selecting the additional runs. This paper gives an in-depth look at fold-over techniques via the following four significant contributions. The first contribution is on discussing the adjusted switching levels fold-over technique to overcome the limitation of the classical one. The second contribution is on presenting a comparison study among the widely used fold-over techniques to help experimenters to recommend a suitable fold-over technique for their experiments by answering the following two fundamental questions: Do these techniques dramatically lessen the confounding of the initial designs, and do the resulting combined designs (combining initial design with its fold-over) via these techniques have considerable difference from the optimality point of view considering the markedly different searching domains in each technique? The optimality criteria are the aberration, confounding, Hamming distance and uniformity. Many of these criteria are given in sequences (patterns) form, which are inconvenient and costly to represent and compare, especially when the designs have many factors. The third innovation is on developing a new criterion (dictionary cross-entropy loss) to simplify the existing criteria from sequence to scalar. The new criterion leads to a more straightforward and easy comparison study. The final contribution is on establishing a general framework for the connections between initial designs and combined designs based on any fold-over technique.

Generalized foldover method for high-level designs

Fractional factorial designs are popularly used in different fields of experimentations, which allow experimenters to study large number of potentially relevant factors with relatively small number of experimental units but suffer from the fact that some of the effects are aliased with some others. In order to overcome these drawbacks, the foldover technique is widely used to de-alias factor effects. This article aims at using the mirror image reflection to augment a given design, to improve its properties in terms of the uniformity criterion measured by Lee discrepancy.

Projection uniformity under mixture discrepancy

The objective of this paper is to discuss the issue of projection uniformity under mixture discrepancy (MD). The uniformity pattern (UP) and minimum projection uniformity criterion are defined for two- and three-level designs under MD. It is shown that the projection uniformity under MD is better than that of other discrepancies, and there is a linear relationship between UP and generalized word-length pattern. Moreover, it is also shown that the foldover technique can increase uniformity resolution. The lower bounds of projection discrepancy for foldover designs and more general follow-up designs are also obtained for two-level designs. For three-level designs, the UP is defined through the average projection discrepancy based on level permutation of factors and its property is also discussed.

Is the End-to-End, Hand-Sewn Anastomosis for Diverting Ileostomy Reversal Less Safe than the Fold-Over Technique?

Is the End-to-End, Hand-Sewn Anastomosis for Diverting Ileostomy Reversal Less Safe than the Fold-Over Technique?

A closer look at de-aliasing effects using an efficient foldover technique

ABSTRACTFoldover techniques are used to reduce the confounding when some important effects (usually lower order effects) cannot be estimated independently. This article develops an efficient foldover mechanism for symmetric or asymmetric designs, whether regular or nonregular. In this paper, we take the uniformity criteria (UC) as the optimality measures to construct the optimal combined designs (initial design plus its corresponding foldover design) which have better capability of estimating lower order effects. The relationship between any initial design and its combined design is studied. A comparison study between the combined designs via different UC is provided. Equivalence between any combined design and its complementary combined design is investigated, which is a very useful constraint that reduce the search space. Using our results as benchmarks, we can implement a powerful algorithm for constructing optimal combined designs. Our work covers as well as gives results better than recent works of about 20 articles in the last few years as special cases. So this article is a good reference for constructing effective designs.

A Secure Technique for Microvascular Anastomosis in Arteries with Intimal Dissection: Intimal Sleeve Fold-Over Technique.

Intimal dissection can cause an irregular internal surface with intimal flaps and subendothelial collagen exposure. This has been associated with a high risk of thrombosis. Trimming the artery to a healthy level is routinely recommended to avoid intimal dissection. However, this method is limited when there is inadequate vascular length to work with. We dealt with an artery exhibiting severe intimal dissection by using a new suture technique: the intimal sleeve fold-over technique. Severe arterial intimal dissections were observed in 9 (6.9%) of 130 arterial microvascular anastomoses in free flap reconstruction for oral cancer patients from January 2013 to December 2013. We used this technique in 6 of the 9 patients. All 6 patients were discharged as scheduled without perioperative problems and complications during follow-ups. The mean diameters of the recipient and pedicle arteries with intimal dissection were 2.13 and 2.20 mm. The mean time for performing sleeve fold-over procedure of on each artery was 5.1 minutes. A secure intima-to-intima contact can be achieved using this technique. This technique can provide an alternative method to intimal dissection when the length of the artery is limited.

The anterolateral thigh fold-over flap for total and subtotal glossectomy reconstruction.

We present a fold-over technique for total and subtotal glossectomy reconstruction utilizing the ALT flap with the goal of increasing soft tissue bulk. Retrospective review of total and subtotal glossectomy patients undergoing ALT fold-over flap reconstruction from January 2007 to December 2012. Eight patients fit inclusion criteria. Average length of follow-up was 35 months. There were no flap failures. At last follow-up, no patients were tracheostomy dependent. Six out of 8 patients (75%) did not require a g-tube and were able to maintain their weight. Speech intelligibility was good in 6/8 patients (75%). The ALT fold-over flap technique provides sufficient bulk to allow decannulation and airway protection as well as PO intake in most patients. Given the minimal donor site morbidity, it is our technique of choice for total and subtotal glossectomy defects. © 2016 Wiley Periodicals, Inc. Microsurgery 36:297-302, 2016.

Foldover Plans for Resolution IV Designs with 11 to 16 Factors

When there is a concern about the best way to apply the foldover technique to a Resolution IV fraction, it is often helpful to consult the literature available. Unfortunately, foldover plans for Resolution IV designs with 11 ≤ k factors are not provided. This article shows a methodology for the selection and classification of foldover plans for two‐level fractional factorial designs with 11 to 16 factors based on an exhaustive search and computer programming. The recommended foldovers are presented. This research extends the current foldover plans available for Resolution IV designs. Copyright © 2015 John Wiley & Sons, Ltd.

On the Use of Semi-folding in Regular Blocked Two-level Factorial Designs

In this article, we consider experimental situations where a blocked regular two-level fractional factorial initial design is used. We investigate the use of the semi-fold technique as a follow-up strategy for de-aliasing effects that are confounded in the initial design as well as an alternative method for constructing blocked fractional factorial designs. A construction method is suggested based on the full foldover technique and sufficient conditions are obtained when the semi-fold yields as many estimable effects as the full foldover.

Endless arguments over diversion stomas.

See Article on Page 118-121 Diversion stoma is an anastomosis protection method frequently used in colorectal surgery. Recent increase of sphincter-preserving surgery, preoperative radiation therapy and laparoscopic surgery has the demand for a diversion ileostomy rising. Accordingly, three have been consistent and diverse arguments about the advantages and the disadvantages of the various methods in creating and restoring the diversion stoma. The typical issues are the pros and the cons for an ileostomy and a colostomy. Evidence is not sufficient to determine which is superior, an ileostomy or a colostomy [1]. Although dehydration and renal failure are concerns with an ileostomy [2, 3], it has become the preferred procedure because of its several advantages: (1) Formation of stoma in the midline of the abdomen is not necessary; (2) Adhesion with the greater omentum is less common than transverse colostomy; (3) Ileostomy is usually safe and anatomically convenient after rectosigmoid colon surgery in which diversion stoma is most commonly needed. In addition, purse-string suture (PSS) as a technique for skin closure has been reported to reduce surgical site infection (SSI) when doing an ileostomy take down [4]. However, whether the anatomical closure of the abdominal wall was performed accurately must be considered if they would compare skin closure methods. In my personal experience, SSI is not a significant problem and the stitches can usually be removed after 1 week, in case of the ileostomy formed within the rectus abdominis muscle, if the peritoneum grown up within the rectus muscle is removed and if the anterior and posterior fascia are closed separately making the naked rectus muscle belly rejoined. Therefore, more evidence is necessary through further research whether PSS which is cosmetically superior but requires laborious dressing during the discharge of 2-3 weeks is worthwhile to replace the primary closure. Cheong et al. [5] mentioned that there were no differences between the fold-over technique and the resection anastomosis technique of ileostomy take down. The fold-over technique can be simpler and be more useful when the distal loop is short. However, it can increase the risk of contamination by bowel content, and the procedure may not be possible when the distal loop has been made narrow to prevent spill over. Many investigators have identified that a randomized, large-scale study is needed in order to reach a firm conclusion, but each surgical procedure has advantages and disadvantages. And controlling all of the factors in a randomized study will not be easy. Therefore, a realistic alternative would be to choose an appropriate method depending on the situation by knowing the arguments and by understanding the advantages and the disadvantages of each procedure in creating and restoring diversion stoma.

Feasibility and safety of a fold-over diverting ileostomy reversal after rectal cancer surgery: case-matched comparison to the resection technique.

PurposeCompared to the stapling technique, the fold-over technique (FO) has the benefit of avoiding the sacrifice of the bowel segment. The aim of this study was to compare short-term outcomes between the FO and a conventional resection.MethodsBetween June 2008 and March 2012, a total of 242 patients who underwent a diverting ileostomy reversal after rectal cancer surgery were selected. Among them, 29 patients underwent the FO. Using propensity scores to adjust for body mass index, previous abdominal surgery history, rectal cancer surgery type (open vs. minimally invasive), and reason for ileostomy (protective aim vs. leakage management), we created a well-balanced cohort by matching each patient who underwent the FO, as the study group, with two patients who underwent a stapled or a hand-sewn technique with bowel resection (RE), as the control group (FO : RE = 1 : 2). Morbidity and perioperative recovery were compared between the two groups.ResultsTwenty-four and forty-eight patients were allocated to the FO and the RE groups, respectively. The mean operation time was 91 ± 26 minutes in the FO group and 97 ± 34 minutes in the RE group (P = 0.494). The overall morbidity rates were not different between the two groups (12.5% in FO vs. 14.6% in RE, P = 1.000). The rate of postoperative ileus was similar between the two groups (8.3% in FO vs. 12.5% in RE, P = 0.710). Although time to resumption of soft diet was shorter in the FO group than in the RE group, the lengths of hospital stay were not different.ConclusionThe FO and the conventional resection have similar short-term clinical outcomes for diverting ileostomy reversal.

OP205: Total glossectomy reconstruction using the foldover anterolateral thigh flap technique

In free flap reconstruction of total glossectomy defects, it is necessary to have sufficient tissue bulk in order to facilitate oropharyngeal squeeze and maintain airway protection. The purpose of this paper is to present our technique of total glossectomy reconstruction with the anterolateral thigh flap utilizing a unique fold-over technique. Retrospective review of total glossectomy patients undergoing ALT fold over flap reconstruction. Demographic and tumor data, surgical therapy, adjuvant therapy, tracheostomy dependence, diet, and disease status at last follow up were recorded. Fold-over flap technique: a de-epithelialized portion of the ALT flap is secured to the mandible with trans-osseous sutures and is used to support the floor of mouth. The epithelialized portion of the flap is sutured into the vallecula and along the alveolar ridge of the mandible resulting in a flap that is folded onto itself with the pedicle exiting through the fold. A hyoid suspension is performed, pulling the larynx superiorly and anteriorly. From 2/2007 to 4/2012, nine patients (six males) underwent fold over flap reconstruction for T3 (five patients) or T4 (four patients) oral tongue and floor of mouth cancer. Average age 51 years (28–61) and average follow up 19 months (2–56). Diet at last follow up: three patients on pureed without G-tube; three patients on liquids and G-tube; three patients on G-tube only (two died within 10 months of surgery due to disease progression). At last follow up two patients had tracheostomy, both with disease progression and death within 3 months of surgery. The ALT fold over flap technique provides sufficient bulk to allow decannulation and airway protection as well as PO intake in most patients undergoing total glossectomy. Given the minimal donor site morbidity with this flap, it is our reconstruction of choice for total glossectomy defects.

Reverse Foldovers for Blocked 2 m−k Fractional Factorial Designs

Two-level regular fractional factorial designs are often used in industry as screening designs to help identify early on in an experimental process those experimental or system variables which have significant effects on the process being studied. When the experimental material to be used in the experiment is heterogenous or the experiment must be performed over several well-defined time periods, blocking is often used as a means to improve experimental efficiency by removing the possible effects of heterogenous experimental material or possible time period effects. In a recent article, Li and Jacroux (2007) suggested a strategy for constructing optimal follow-up designs for blocked fractional factorial designs using the well-known foldover technique in conjunction with several optimality criteria. In this article, we consider the reverse foldover problem for blocked fractional factorial designs. In particular, given a 2(m+p)−(p+k) blocked fractional factorial design D, we derive simple sufficient conditions which can be used to determine if there exists a 2(m+p−1)−(p−1+k+1) initial fractional factorial design d which yields D as a foldover combined design as well how to generate all such d. Such information is useful in developing an overall experimental strategy in situations where an experimenter wants an overall blocked fractional factorial design with “desirable” properties but also wants the option of analyzing the observed data at the halfway mark to determine if the significant experimental variables are obvious (and the experiment can be terminated) or if a different path of experimentation should be taken from that initially planned.

On the use of partial confounding for the construction of alternative regular two-level blocked fractional factorial designs

In this paper, we consider experimental situations in which a regular fractional factorial design is to be used to study the effects of m two-level factors using n=2 m− k experimental units arranged in 2 p blocks of size 2 m− k− p . In such situations, two-factor interactions are often confounded with blocks and complete information is lost on these two-factor interactions. Here we consider the use of the foldover technique in conjunction with combining designs having different blocking schemes to produce alternative partially confounded blocked fractional factorial designs that have more estimable two-factor interactions or a higher estimation capacity or both than their traditional counterparts.

An algorithmic foldover procedure for nearly orthogonal arrays with projection

Nearly orthogonal arrays are a class of experimental designs that are useful for accommodating multiple mixed-level factors and small run sizes for factor screening experiments. Several algorithmic approaches have been used to construct such arrays using D, A, ave(S2), and most interestingly, projection properties to evaluate and classify candidate arrays. Nearly orthogonal arrays constructed to contain good projection properties make it possible to estimate higher order interactions for subsets of design columns but can introduce significant correlation as to make some factor estimates terribly imprecise. This paper proposes a method to exploit the projection properties of these nearly orthogonal arrays while guarding against correlated factor effects. The usefulness of this foldover technique is demonstrated by a live-virtualconstructive simulation experiment.

Preference Of Patients And Physicians Concerning Treatment Options For Relapsed Follicular Lymphoma: A Discrete Choice Experiment

Abstract 4350 Background Patients with symptomatic relapsed follicular lymphoma, together with their physicians, must choose between a variety of treatment options, including conventional chemotherapy, radioimmunotherapy, and high-dose chemotherapy with subsequent autologous or allogeneic transplantation. These treatments vary with respect to effectiveness and tolerability. The purpose of this study was to elicit preference for the treatment options particular to relapsed follicular lymphoma and the attributes associated with the treatment options amongst patients in Alberta, and hematologists and medical oncologists in Canada who treat lymphoma, using a discrete choice experiment (DCE). Methods Background information and a questionnaire containing the DCE was mailed to 180 patients age 18 to 65 years and 252 hematologists and medical oncologists. The treatment attributes chosen for the DCE included: administration protocol, toxicity, average remission length and cost. For administration protocol and toxicity, there were 4 categorical levels describing the varying scenarios for standard chemotherapy (CT), radio-immunotherapy (RIT), high dose chemotherapy and autologous stem cell transplantation (AUTO), and allogeneic stem cell transplantation (ALLO). For average remission length, there were two numerical levels: 1 year (CT/RIT) and 5 years (AUTO/ALLO). For cost, four numerical levels were chosen to reflect current clinic/hospital expenditure: $5000 (CT), $25,000 (RIT), $50,000 (AUTO) and $150,000 (ALLO). A fractional factorial design was chosen to examine main effects and a fold-over technique was used to create multiple choice questions. In the series of multiple choice questions, respondents were asked to choose between two unlabeled treatment options, described according to the attributes where the attribute levels were different for each option. Descriptive statistics were applied to participant demographic and clinical data. The DCE was analyzed using a random effects logit model. Marginal rates of substitution calculated from regression coefficients provided information about preference for the treatment attributes. A post-estimation technique was used to predict uptake of the four treatment options. Results 81 patients (45%) and 48 physicians (19%) completed the questionnaire. Responding patients had a mean age of 54.7 years and were on average 4.4 years from initial diagnosis. 93% of patients received prior chemotherapy and 24% had received a prior stem cell transplant. 48% of patients had not yet relapsed and 33% were currently symptomatic. Physicians were predominantly hematologists (93%) who have been in practice on average for 12.2 years. 46% of physicians reported being in a practice that includes stem cell transplantation. Preferences of patients and physicians were similar. For all participants, remission length and the lesser toxicity of RIT compared with CT were found to be positive influences on choice (p<0.0001 and p=0.057, respectively). Negative influences on choice included toxicity of both AUTO and ALLO compared with CT (p=0.047 and p<0.0001, respectively), and cost (p<0.0001). Participants required a remission length of 0.6 years to accept the toxicity of AUTO but 3.9 years to accept the toxicity of ALLO. In relation to cost, participants thought it was acceptable for the health care system to pay $340, 000 per each 1 year increase in remission length. Post-estimation technique to evaluate distribution of preference for treatment options revealed that patients were most likely to choose AUTO (69%) and less likely to choose RIT (14%), CT (11%), and ALLO (7%). The distribution for physicians was similar: AUTO (56%), RIT (20%), CT (19%), and ALLO (4%). Conclusions This discrete choice experiment shows that patients with relapsed follicular lymphoma are able to consider the advantages and disadvantages of various treatment options, and appear to be willing to trade off the toxicity associated with autologous transplantation in order to benefit from increased remission length. Disclosures: Shafey: Glaxo-Smith-Kline: Research Funding. Stewart: Glaxo-Smith-Kline: Research Funding. Do: Roche: Honoraria; Sanofi-Aventis: Honoraria, Research Funding.

Preference of Patients and Physicians Concerning Treatment Options for Relapsed Follicular Lymphoma: A Discrete Choice Experiment.

Abstract 4350 BackgroundPatients with symptomatic relapsed follicular lymphoma, together with their physicians, must choose between a variety of treatment options, including conventional chemotherapy, radioimmunotherapy, and high-dose chemotherapy with subsequent autologous or allogeneic transplantation. These treatments vary with respect to effectiveness and tolerability. The purpose of this study was to elicit preference for the treatment options particular to relapsed follicular lymphoma and the attributes associated with the treatment options amongst patients in Alberta, and hematologists and medical oncologists in Canada who treat lymphoma, using a discrete choice experiment (DCE). MethodsBackground information and a questionnaire containing the DCE was mailed to 180 patients age 18 to 65 years and 252 hematologists and medical oncologists. The treatment attributes chosen for the DCE included: administration protocol, toxicity, average remission length and cost. For administration protocol and toxicity, there were 4 categorical levels describing the varying scenarios for standard chemotherapy (CT), radio-immunotherapy (RIT), high dose chemotherapy and autologous stem cell transplantation (AUTO), and allogeneic stem cell transplantation (ALLO). For average remission length, there were two numerical levels: 1 year (CT/RIT) and 5 years (AUTO/ALLO). For cost, four numerical levels were chosen to reflect current clinic/hospital expenditure: $5000 (CT), $25,000 (RIT), $50,000 (AUTO) and $150,000 (ALLO). A fractional factorial design was chosen to examine main effects and a fold-over technique was used to create multiple choice questions. In the series of multiple choice questions, respondents were asked to choose between two unlabeled treatment options, described according to the attributes where the attribute levels were different for each option. Descriptive statistics were applied to participant demographic and clinical data. The DCE was analyzed using a random effects logit model. Marginal rates of substitution calculated from regression coefficients provided information about preference for the treatment attributes. A post-estimation technique was used to predict uptake of the four treatment options. Results81 patients (45%) and 48 physicians (19%) completed the questionnaire. Responding patients had a mean age of 54.7 years and were on average 4.4 years from initial diagnosis. 93% of patients received prior chemotherapy and 24% had received a prior stem cell transplant. 48% of patients had not yet relapsed and 33% were currently symptomatic. Physicians were predominantly hematologists (93%) who have been in practice on average for 12.2 years. 46% of physicians reported being in a practice that includes stem cell transplantation. Preferences of patients and physicians were similar. For all participants, remission length and the lesser toxicity of RIT compared with CT were found to be positive influences on choice (p<0.0001 and p=0.057, respectively). Negative influences on choice included toxicity of both AUTO and ALLO compared with CT (p=0.047 and p<0.0001, respectively), and cost (p<0.0001). Participants required a remission length of 0.6 years to accept the toxicity of AUTO but 3.9 years to accept the toxicity of ALLO. In relation to cost, participants thought it was acceptable for the health care system to pay $340, 000 per each 1 year increase in remission length. Post-estimation technique to evaluate distribution of preference for treatment options revealed that patients were most likely to choose AUTO (69%) and less likely to choose RIT (14%), CT (11%), and ALLO (7%). The distribution for physicians was similar: AUTO (56%), RIT (20%), CT (19%), and ALLO (4%). ConclusionsThis discrete choice experiment shows that patients with relapsed follicular lymphoma are able to consider the advantages and disadvantages of various treatment options, and appear to be willing to trade off the toxicity associated with autologous transplantation in order to benefit from increased remission length. Disclosures:Shafey:Glaxo-Smith-Kline: Research Funding. Stewart:Glaxo-Smith-Kline: Research Funding. Do:Roche: Honoraria; Sanofi-Aventis: Honoraria, Research Funding.

Preference for breast cancer risk reduction hormonal therapy in women age 50-69 years attending screening mammography.

Abstract Abstract #3100 Background: It is expected that tamoxifen, raloxifene and aromatase inhibitors (AIs) will become available for the indication of breast cancer prevention in postmenopausal women. It is unknown how women weigh the benefits and disadvantages of these drugs. The aim of this study was to elicit preferences, using a discrete choice experiment (DCE), for attributes of breast cancer risk reduction hormonal therapies amongst women age 50 – 69 years who attend screening mammography.&amp;#x2028; Methods: 500 potentially eligible women were randomly sampled from a screening mammography database (SMD). Women permitting contact from the investigators were invited to participate. Demographic and breast cancer risk factor data was collected from the SMD for participants and non-participants, and compared. The DCE was administered via a postal survey. The attributes and levels for the DCE are outlined in Table 1. A fractional factorial design and matched fold-over technique yielded 16 choice sets. Two dominant choice sets were added. For each choice set, respondents were asked to mark preference for Drug A, Drug B or Neither. The DCE was analyzed using conditional logistic regression (CLR). Regression post estimation calculations (RPECs) were used to predict chemoprevention uptake.&amp;#x2028; &amp;#x2028; Results: 111 women agreed to be contacted by the investigators, 94 agreed to be sent a survey and 79 returned a completed questionnaire. The proportions of participants who were nulliparous or had a predicted 5-year breast cancer risk &amp;gt;1.66% were significantly higher than for non-participants (p&amp;lt;0.05). No differences were found for age, education or mammographic breast density. From the CLR, all attributes, except decreased risk bone fracture, had coefficients that were significantly different from zero (p&amp;lt;0.01) and of the expected sign. RPECs suggest that the uptake of tamoxifen, raloxifene and AIs would be 13%, 50% and 23% respectively, and that 14% would not consider chemoprevention.&amp;#x2028; &amp;#x2028; Conclusions: The most important attribute in women's selection of a prevention drug was breast cancer risk reduction. However, the following attributes were still important negative influences on choice: increased risk bone fracture &amp;gt; endometrial cancer &amp;gt; venous thromboembolic event &amp;gt;&amp;gt; cost. Raloxifene may be favoured if all three agents were available. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3100.

Blocking in two-level non-regular fractional factorial designs

In this paper we consider screening experiments where a two-level fractional factorial design is to be used to identify significant factors in an experimental process and where the runs in the experiment are to occur in blocks of equal size. A simple method based on the foldover technique is given for constructing resolution IV orthogonal and non-orthogonal blocked designs and examples are given to illustrate the process.

Optimal Foldover Plans for Two-Level Fractional Factorial Split-Plot Designs

We consider the construction of foldovers of two-level fractional factorial split-plot designs. As a follow-up strategy, the foldover technique is useful when the objective is to systematically de-alias effects of interest after the initial fractional factorial split-plot design has been run. Due to the sequential nature in which the runs of the initial and foldover designs are conducted, the resulting combined design (the design consisting of both the initial design and its foldover) is a blocked fractional factorial split-plot design. Using the minimum aberration criterion for blocked fractional factorial split-plot designs, in conjunction with other optimality criteria, we provide a catalog of optimal foldover plans for initial minimum aberration fractional factorial split-plot designs consisting of 16 and 32 runs.