|
It means that three-tenths of the plaque is removed. It's nonsense, because plaque is a categorical variable, so percents don't make sense. It's nonsense, because removing 100 percent of the plaque already removes all of it. It means that there is 3 times as much plaque before using the rinse as there is after using it. An ad for a new mouth rinse says that it "reduces plaque on teeth by 300%". What does this mean? You measure the age (years), weight (pounds), and marital status (single, married, divorced, or widowed) of 1400 women. How many variables did you measure? 1400 one two three In January of 1997, the price of Intel common stock rose from $131 per share to $162 per share. (Intel makes the processors for the computers you have been happily using.) What percent increase is this? 19.1% 23.7% 80.9% 123.7% Michelle's income two years ago was $420,000. Last year her income was only $100,000. The percent change in Michelle's income was 76.2% decrease 320% decrease 31.3% decrease None of these The telephone company says that 62% of all residential phone numbers in Los Angeles are unlisted. A telephone survey contacts a random sample of 1000 Los Angeles telephone numbers, of which 58% are unlisted. In this setting,
62% is a parameter and 58% is a statistic 58% is a parameter and 62% is a statistic 62% and 58% are both parameters 58% and 62% are both statistics In a table of random digits, a specific pair such as 00 cannot be repeated until all other pairs have appeared the pair 00 can appear, but 000 is not random and can never appear in the table any pair of entries is equally likely to be any of the 100 possible pairs 00, 01, 02, . . . , 99 each pair of digits 00, 01, 02, . . . , 99 appears exactly once in any row of the table Your statistics class has 30 students. You want to call an SRS of 5 students from your class to ask where they use a computer for the online exercises. You label the students 01, 02, . . . , 30. You enter the table of random digits at this line:
14459 26056 31424 80371 65103 62253 22490 61181
Your SRS contains the students labeled 14, 45, 92, 60, 56 14, 31, 03, 10, 22 14, 03, 10, 22, 22 14, 03, 10, 22, 06 When we take a census, we attempt to collect data from a stratified random sample a convenience sample every individual selected in a simple random sample every individual in the population A national sample survey interviewed 3,800 people age 18 and older nationwide by telephone. One question asked was whether they agreed with this statement: "Some people say we should have a third major political party in this country in addition to the Democrats and Republicans."
53% of the people asked agreed that we should have a third party. The number 53% is a margin of error statistic. parameter. correlation. |