Muscle strength is crucial for good health. Strong muscles strengthen bones, control blood sugar, improve cholesterol levels, maintain a healthy weight, reduce joint pain, and fight mild depression. Shopping Cart Description Qty Price The Harvard Medical School 6-Week Plan for Healthy Eating (Print - Free U. Tips to measure your blood pressure correctly To determine whether you have hypertension, a medical professional will take a blood pressure reading.
An important concept that is crucial to the understanding of cognitive health is known as cognitive reserve. How memory and thinking ability change with age Scientists used to think that brain connections developed at a rapid pace in the first few years of life, until you reached your mental peak in your early 20s.
Inside Pain: Arthritis Back Pain Headache Joint Replacement Other Pain Featured Content: Can spinal manipulation ease my low back pain. Improving your mobility A fundamental goal of healthy aging is to keep walking as long as possible. What you should know about magnesium You need magnesium for many tasks. Do gel manicures increase cancer risk. The level of risk from UVA radiation delivered by lamps used by professional manicurists to dry gel nail polish increases with the frequency of manicures.
What to do about mild hypothyroidism is a subject that has been studied and debated for years. Does osteoporosis cause any symptoms. Osteoporosis is not always symptomatic, so screening for the condition is recommended. Why do I lose a lot of hair each fall. Hair growth is cyclic, with more shed during the fall than at other times of the year. These seven tips can keep your strength training safe and effective.
Warm up and cool down for five to 10 minutes. Focus on form, not weight. Align your body correctly and move smoothly through each exercise. Poor form can prompt injuries and slow gains. When learning a strength training routine, many experts suggest starting with no weight, or very light weight. Concentrate on slow, smooth lifts and equally controlled descents while isolating a muscle group. Working at the right tempo helps you stay in control rather than compromise strength gains through momentum.
For example, count to three while lowering a weight, hold, then count to three while raising it to the starting position. Pay attention to your breathing during your workouts. Keep challenging muscles by slowly increasing weight or resistance. The right weight for you differs depending on the exercise. Choose a weight that tires the targeted muscle or muscles by the last two repetitions while still allowing you to maintain good form.
If you can't do the last two reps, choose a lighter weight. When it feels too easy to complete add weight (roughly 1 to 2 pounds for arms, 2 to 5 pounds for legs), or add another set of repetitions to your workout (up to three sets).
If you add weight, remember that you should be able to do all the repetitions with good form and the targeted muscles should feel tired by the last two. Stick with your routine working all the major muscles of your body two or three times a week is ideal. You can choose to do one full-body strength workout two or three times a week, or you may break your strength workout into upper- and lower-body components.The University-wide competition awards financial support toward the completion of the candidate's dissertation.
Faculty Professional Service Honor Prof. Per Mykland, Robert Maynard Hutchins Distinguished Service Professor, is the new president of the Society for Financial Econometrics for 2017-19.
Michael Stein Awarded the Arthur L. Michael Stein has been awarded the Arthur L. Kelly Prize for exceptional service in the Physical Sciences Division. The Kelly Prize will be awarded at the PSD Convocation ceremony on June 10. The Statistics Consulting Program The Department of Statistics Consulting Program is now open and receiving project requests for the new academic year. Degree in Computational and Applied Mathematics The University of Chicago has recently approved a new degree-granting Ph.
The program will be jointly administered by faculty in a number of departments (Statistics, Mathematics, Computer Science and others) in a formal framework called the Committee on Computational and Applied Mathematics (CCAM).Cell Selection and Check Box Selection with React Data Grid Rows
Information about the Ph. Home Contacts Department Directory Administrative Staff Faculty Emeriti Faculty Visiting Faculty Postdoctoral Scholars M. Students Faculty In Memoriam M.
Program About Our M. Program Faculty Research Domains Orientation Schedule Student Offices Student Representatives Guide for Degree Programs Requirements and Regulations for M. Candidates Policy Concerning Master's Degree Registration Graduate Courses and Grades Ph. Home People Contacts Department Directory Administrative Staff Faculty Emeriti Faculty Visiting Faculty Postdoctoral Scholars M. Program Faculty Research Domains Students Orientation Schedule Student Offices Student Representatives Guide for Degree Programs Requirements and Regulations for M.
News Best wishes to our department's Autumn Quarter graduates. Department Events This Week SATURDAY, December 9, 2017, Autumn Quarter ends Wishing you a safe and happy holiday season. Workshop on Labour Statistics-30 August 2017 Statistics Mauritius is the official organisation responsible for collection, compilation, analysis and dissemination of the official statistical data relating to the economic and social activities of the country.
You may be trying to access this site from a secured browser on the server. Please enable scripts and reload this page.
Each year Africa celebrates this day to raise public awareness of the importance of statistics in all aspects of social and economic life. Julien (Haut de Flacq) St.We are in our 70's and probably won't get back to Norway, but we will tell anyone who is willing to listen that Nordic Visitor and Kolbrun are first class.
As far as Norway itself goes, it has to be one of the most beautiful places on earth. And our tour hit some of the loveliest of Norway. When we first decided to use Nordic Visitor we thought the cost was a little steep. But having had the experience, it was worth every penny.
Thanks for a fantastic experience. Terri, United States Sweden's Top Three by Train, September 2016 Hotel accommodations very nice, excellent big breakfasts at all hotels. Convenient location to train stations. It was truly a relaxing and no stress tour for myself and my 86-year old father. Irja did an excellent job of customizing the tour for us. John, United Kingdom South Iceland at Leisure, September 2016 We really appreciated the arrangements made by Nordic Visitor.
It dramatically lowered our stress level as we contemplated our first visit to such an unfamiliar place. Each day on our trip, we realized how good a job Nordic Visitor had done. We loved our trip to a wonderful place.
We will recommend Nordic Visitor to anyone who asks. Scott, United States Romance Around Iceland, September 2016 Honestly felt nothing was left out and the trip couldn't have gone any better and all 6 of us that were on this are in full agreement on that. Maureen, Canada Iceland Grand Tour, September 2016 You have a very beautiful country with wonderful friendly people to deal with. There are so many natural wonders to see and experience and we loved it all, a true nature lover's paradise.
We were impressed by the cleanliness of the country, which shows pride in your environment. Ever person we met and spoke with, were so helpful and not only interested in talking proudly of their home, but took interest in us as well.
Thank you for making our holiday very memorable. Brian, United States South and West in Detail, August 2016 We had an amazing experience from start to finish.A wrench may slip, damaging the bowl and bloodying your knuckles.
Make sure you don't fall for these common toilet mistakes, either. At the end of the day, my material cost is between 25-30 percent of the cost of the job. You need to shut the water off from the inside. We have to fix tons of these in the spring mostly because people leave their outside hoses connected and they freeze up.
Look for a company that warranties its service for up to a year for major installations or repairs. Here are more tips to save on every household bill.
Same goes for checking your water pressure. We said fine, but she ended up not returning until four hours later. We tried holding her. She just kept crying. There is no national standard for issuing licenses. Some plumbers are licensed by the state, others by the counties they work in.
Check with your local city hall or chamber of commerce. They should be able to direct you to the appropriate source for a list of licensed plumbers in your area. They come and go. Instead, look for a plumber who is well-established in your community. Check the Better Business Bureau and read customer reviews at sites such as HomeAdvisor, Angie's List, or Citysearch. Local contractors or plumbing fixture stores can also refer you to a quality plumber, according to Grady Daniel, who owns a plumbing company in Austin, Texas.
A trusted plumber that consistently delivers quality service does not remain a secret for very long. Estimates for an average-sized job should be within a few hundred dollars. Be suspicious of anything that is substantially lower or double the price of the rest, and watch out for hidden fees, like charges for travel expenses.
They could be signs of a home improvement scam. A good plumber will not nickel and dime you like this, and many of us will offer free estimates. Get a clueand an electrician.
By staying smart and doing these things all smart homeowners do once a year, you won't need to call me as often. We may be tiny buggers (about the shape and size of an apple seed), but our presence elicits a massive case of the heebie jeebies. Home fires can happen quickly, devastating lives and property, but unlike other disasters, most home fires can be prevented.Thank you to Nordic Visitor for all your help xx AZDesertDancer, United States Express Iceland, July 2015 Hafdis was our advisor with Nordic Visitor.
Row8on, United States Exotic Hideaways, July 2015 Spent 7 days 6 night in Iceland and our trip was organized by Nordic Visitor Tours. Deborah, United States Scenic Fjords of Norway, July 2015 All lodging and transportation worked perfectly. Joan, United States Majestic Highlights of Norway, July 2015 We are very busy and using Nordic Visitor made our trip to Norway very pleasant and stress free.
Barbara, United Kingdom Ultimate Journey of Norway, July 2015 WE are widely travelled and this tour is a highlight. Michele, United States Golden Route of the Nordic Countries, July 2015 Everything was wonderful, you more than met our expectations.
Michael, China Romantic Capitals of Scandinavia, July 2015 All hotels were excellent. Communication was outstanding all the way through the process. Andy Guy Golden Circle and South Coast, July 2015 We both felt the whole package was really well organised and structured.
Kathryn, United States Pearls of North Iceland, July 2015 Iceland was a wonderful experience -- the scenery, the culture, the history, the colorful houses, the sheep and horses in their wide-open spaces, the fascinating geology, and even the language. Michael, United States South Iceland at Leisure, July 2015 The itinerary, highlighted map, mobile phone, and GPS with the rental car were all very helpful.
Kevin, Canada Iceland Full Circle, July 2015 I travel around the world and have been in every continent and used many travel agencies.
Daniel, Canada Iceland Full Circle, July 2015 On our customized map, there were a few notes such as "home made ice cream", or "cozy coffee shop". The Garbo family, United States Express Iceland, July 2015 Everything was excellent.
Melissa, United States The Natural Wonders of Iceland, June 2015 Our guide Alfred Moller was terrific. Sharyn, Australia Fjords to Glaciers, June 2015 Kolbrun was wonderful.
Amy, United States express iceland, June 2015 Customer service was exceptional right from the beginning. Russel, United States express iceland, June 2015 The trip was great and the island beautiful. John and Martha, Canada express iceland, June 2015 The services provided by Sjofn exceeded our expectations in all respects.
Nancy, United States South Iceland at Leisure, June 2015 We thought that Larus did an excellent job in planning the tour and our hotel stops based on our interests, which were largely to take advantage of seeing the beautiful scenery and to hike.
James, United States Iceland Full Circle, June 2015 Everything about this tour was perfect. You will hear from me someday in the future for more travel.
Brie and Pat, United States Iceland Full Circle, June 2015 We booked a last minute honeymoon trip with Nordic Visitor and found the service outstanding. Margarete Ritchie, Sweden Custom Booking, June 2015 You provide a good service to people like us who come from so far away and don't know how to get accommodation etc. Alexandra had booked and organised a self drive holiday around Iceland for us in 2011 Jane, United Kingdom Golden Triangle - Starting in Copenhagen, June 2015 Hotels were all in really good, central positions, close to transport links and city centres.
Catherine, United Kingdom South Iceland at Leisure, June 2015 We had a great holiday in Iceland with the whole itinerary organised by Nordic Visitor including all the hotels and the hire car. Donna, United Kingdom Iceland Full Circle, June 2015 Booked a 10 day self drive tour of Iceland via Nordic Visitor.To use a sample as a guide to an entire population, it is important that it truly represents the overall population.
Representative sampling assures that inferences and conclusions can safely extend from the sample to the population as a whole. A major problem lies in determining the extent that the sample chosen is actually representative. Statistics offers methods to estimate and correct for any bias within the sample and data collection procedures.
There are also methods of experimental design for experiments that can lessen these issues at the outset of a study, strengthening its capability to discern truths about the population. Sampling theory is part of the mathematical discipline of probability theory.
Probability is used in mathematical statistics to study the sampling distributions of sample statistics and, more generally, the properties of statistical procedures. The use of any statistical method is valid when the system or population under consideration satisfies the assumptions of the method.
The difference in point of view between classic probability theory and sampling theory is, roughly, that probability theory starts from the given parameters of a total population to deduce probabilities that pertain to samples. Statistical inference, however, moves in the opposite directioninductively inferring from samples to the parameters of a larger or total population.
A common goal for a statistical research project is to investigate causality, and in particular to draw a conclusion on the effect of changes in the values of predictors or independent variables on dependent variables. There are two major types of causal statistical studies: experimental studies and observational studies. In both types of studies, the effect of differences of an independent variable (or variables) on the behavior of the dependent variable are observed.
The difference between the two types lies in how the study is actually conducted. Each can be very effective. Instead, data are gathered and correlations between predictors and response are investigated. Experiments on human behavior have special concerns. The famous Hawthorne study examined changes to the working environment at the Hawthorne plant of the Western Electric Company.
The researchers were interested in determining whether increased illumination would increase the productivity of the assembly line workers.
The researchers first measured the productivity in the plant, then modified the illumination in an area of the plant and checked if the changes in illumination affected productivity. It turned out that productivity indeed improved (under the experimental conditions). However, the study is heavily criticized today for errors in experimental procedures, specifically for the lack of a control group and blindness.
The Hawthorne effect refers to finding that an outcome (in this case, worker productivity) changed due to observation itself. Those in the Hawthorne study became more productive not because the lighting was changed but because they were being observed. This type of study typically uses a survey to collect observations about the area of interest and then performs statistical analysis. In this case, the researchers would collect observations of both smokers and non-smokers, perhaps through a cohort study, and then look for the number of cases of lung cancer in each group.
Various attempts have been made to produce a taxonomy of levels of measurement. The psychophysicist Stanley Smith Stevens defined nominal, ordinal, interval, and ratio scales. Nominal measurements do not have meaningful rank order among values, and permit any one-to-one transformation. Ordinal measurements have imprecise differences between consecutive values, but have a meaningful order to those values, and permit any order-preserving transformation.
Interval measurements have meaningful distances between measurements defined, but the zero value is arbitrary (as in the case with longitude and temperature measurements in Celsius or Fahrenheit), and permit any linear transformation. Ratio measurements have both a meaningful zero value and the distances between different measurements defined, and permit any rescaling transformation. Because variables conforming only to nominal or ordinal measurements cannot be reasonably measured numerically, sometimes they are grouped together as categorical variables, whereas ratio and interval measurements are grouped together as quantitative variables, which can be either discrete or continuous, due to their numerical nature.
Such distinctions can often be loosely correlated with data type in computer science, in that dichotomous categorical variables may be represented with the Boolean data type, polytomous categorical variables with arbitrarily assigned integers in the integral data type, and continuous variables with the real data type involving floating point computation.
But the mapping of computer science data types to statistical data types depends on which categorization of the latter is being implemented.Pairwise Deletion of Missing Data.
Only this way will you get a "true" correlation matrix, where all correlations are obtained from the same set of observations. However, if missing data are randomly distributed across cases, you could easily end up with no "valid" cases in the data set, because each of them will have at least one missing data in some variable.
The most common solution used in such instances is to use so-called pairwise deletion of missing data in correlation matrices, where a correlation between each pair of variables is calculated from all cases that have valid data on those two variables.
However, it may sometimes lead to serious problems. For example, a systematic bias may result from a "hidden" systematic distribution of missing data, causing different correlation coefficients in the same correlation matrix to be based on different subsets of subjects. In addition to the possibly biased conclusions that you could derive from such "pairwise calculated" correlation matrices, real problems may occur when you subject such matrices to another analysis (e.
Thus, if you are using the pairwise method of deleting the missing data, be sure to examine the distribution of missing data across the cells of the matrix for possible systematic "patterns. If the pairwise deletion of missing data does not introduce any systematic bias to the correlation matrix, then all those pairwise descriptive statistics for one variable should be very similar. However, if they differ, then there are good reasons to suspect a bias.
For example, if the mean (or standard deviation) of the values of variable A that were taken into account in calculating its correlation with variable B is much lower than the mean (or standard deviation) of those values of variable A that were used in calculating its correlation with variable C, then we would have good reason to suspect that those two correlations (A-B and A-C) are based on different subsets of data, and thus, that there is a bias in the correlation matrix caused by a non-random distribution of missing data.
Pairwise Deletion of Missing Data vs. Another common method to avoid loosing data due to casewise deletion is the so-called mean substitution of missing data (replacing all missing data in a variable by the mean of that variable).
Mean substitution offers some advantages and some disadvantages as compared to pairwise deletion. Its main advantage is that it produces "internally consistent" sets of results ("true" correlation matrices). The main disadvantages are:Spurious Correlations.
There is a third variable (the initial size of the fire) that influences both the amount of losses and the number of firemen. If you "control" for this variable (e. The main problem with spurious correlations is that we typically do not know what the "hidden" agent is. However, in cases when we know where to look, we can use partial correlations that control for (partial out) the influence of specified variables. Are correlation coefficients "additive. For example, an average of correlation coefficients in a number of samples does not represent an "average correlation" in all those samples.
In cases when you need to average correlations, they first have to be converted into additive measures. For example, before averaging, you can square them to obtain coefficients of determination, which are additive (as explained before in this section), or convert them into so-called Fisher z values, which are also additive.
How to Determine Whether Two Correlation Coefficients are Significant. A test is available that will evaluate the significance of differences between two correlation coefficients in two samples. The outcome of this test depends not only on the size of the raw difference between the two coefficients but also on the size of the samples and on the size of the coefficients themselves.
Consistent with the previously discussed principle, the larger the sample size, the smaller the effect that can be proven significant in that sample. In general, due to the fact that the reliability of the correlation coefficient increases with its absolute value, relatively small differences between large correlation coefficients can be significant.