# Statistics

## Statistics deals with collecting, organizing, and interpreting numerical data. An important aspect of statistics is the analysis of population characteristics inferred from sampling.

### What is the percent error formula? Percent Error is the difference between the true value and the estimate divided by the true value and the result is multiplied by 100 to make it a percentage. The percent error obviously can be positive or negative; however, some prefer taking the absolute value of the difference. The formula is the absolute value of the experimental value (minus) the theoretical value divided by theoretical value times 100. % error = (|Your Result - Accepted Value| / Accepted Value) x 100

### Is income a ratio or interval scale measurement? Income is a ratio measure. In ratio measures, one can order categories, specify the difference between two categories, and the value of zero on the variable represents the absence of the variable. Thus, income can take on values of \$0, \$10, \$30,000, etc. Zero dollar income means the absence of income, making income a ratio measurement.

### A nominal scale variable is? Descriptive, non-numeric, qualitative. Furthermore, they cannot be ordered (as in small, medium, large)

### What is the value of z if the area between -z and z is 0.754? Since the normal distribution is symmetric, the area between -z and 0 must be the same as the area between 0 and z. Using this fact, you can simplify this problem to finding a z such that the area between 0 and z is .754/2=.377. If you look this value up in a z-table or use the invNorm on a calculator, you will find that the required value of z will be 1.16. Therefore, the area between -1.16 and 1.16 must be approximately .754.

### What event has a probability of 0? -- The freezing over of Hell. -- A confirmed sighting of flying pigs. etc. Besides anything that is impossible, as noted above, the simultaneous occurrence of two mutually exclusive events has a probability of zero: It is raining and it is not raining, it is on and it is off, etc.

### What does CL mean in mathematical terms? It may stand for the number 150 (Roman numbers). In statistics, CL usually refers to "Confidence Level," which establishes a likelihood (typically 90 or 95%) an estimated value will fall within a given Confidence Interval (a range of estimated values). For example... [I'll get more done on this later]

### What is the meaning if the examinee has a percentile rank of 79 in the entrance test? It means 79 percent of the people did not was well as he or she did. It also means 21 percent of the people did better.

### How many four digit numbers are made of odd number? If you're asking for 4 digit numbers where all four digits are odd, then the lowest number possible is 1111, and the highest is 9999. You only have 5 digits to work with. The answer is: 54 - 53 = 625 - 125 = 500. Subtract the 5 cubed for the numbers less than 1111, which are not four digits.

### What is the probability of obtaining exactly 4 heads in 6 flips of a fair coin? The probability of a head in one flip is 1/2. The probability of HHHHTT is (1/2)6 = 1/64 The possible correct flips are HHHHTT, HHHTHT, HHTHHT, HTHHHT, THHHHT, HHHTTH, HHTHTH, HTHHTH, THHHTH, HHTTHH, HTHTHH, THHTHH, HTTHHH, THTHHH, TTHHHH, each with a probability of 1/64. Total probability is 15/64.

### What lottery number occurs most often? Please try and understand the enormity of what you are asking, as this question has come up before. Lottery "numbers" are a series. Various balls or slips or number segments are generated, typically with two digits a piece, and a certain number of pieces selected. Thus there might be six balls each with a two digit number on them. I cannot conceive, given the thousands of lottery game types - let alone how many times each has been played - that there is any meaningful way of comparing the data of one game to the next, so that if 12 54 23 84 33 03 came up on a lottery ball drawing in Indiana on March 22, 1994 and the same series came up on a card in New Jersey in August 9, 2007 that we would know. Nor would it actually mean anything. In the event that we found (by someone crunching vast amounts of data from dozens of states) some one series that showed up a bit more often, it would be meaningless. If you flip a coin ten times, it is probable that there may be more times where it is one tihng than another. 6 heads and 4 tails. This does not then make "heads" likely to occur "more often". Just means it did that time. If any number series has repeated - and I'm sure some have - it would not mean a thing. 17 different series might have had instances where they repeated twice. 5 may have had it happen 3 times. Maybe there is one out there that repeated 12 times! But I can assure you that the little balls in the hopper are not aware of it, nor the number generator, nor any other device. Like the coin, it cannot "know" what has been picked or won before. The odds are therefore always the same. Flip a coin ten times, and in the unlikely event that it came up heads ten times...it will still be a fifty/fifty chance on the next flip. Here is the short way to know the number that will always occur "most often": By the odds clearly stated - usually on the ticket itself - the most often chose number...will not be your's.

### How do you do a stem and leaf graph with money? Instead of 4|5 meaning say 4.5 have it mean £4.50 so like £|pence or if in whole numbers just the same 4|5 means £45

### What does a frequency chart or table look like? Another name for a frequency chart is a stem and leaf plot. EXAMPLE: If i have the numbers 72,73, 74, 87, 88. 92,99 First you need to order them into least to greatest. DEFINITIONS stem- (basically like the tens) so 73's stem is 7 leaf- (basically like the ones) so 73's leaf is 3 Stem l Leaf ____________ 7 l 2,3,4 8 l 7,8 9 l 2, 9 In the graph I've shown you I've numbered the numbers from least to greatest going vertically (stem) horizontally (leaf) IT IS INCORRECT IF THEY'RE NOT IN LEAST TO GREATEST ORDER ON STEM AND LEAF