Sampling bias is introduced when the sample used is not representative of a population or inappropriate for the question asked. The sample needs to be big enough to get a good average value (sample size). The composition of the sample must reflect the composition of the population (selection of sample).

Measurement bias appears when the method of data collection is chosen in such a way that the data collected will not best match reality. We need to evaluate the technique: are the measurements taken accurately and no additions will influence the results and the experiment is designed to isolate the effect of multiple factors. Measurement bias results from poorly measuring the outcome you are measuring.

PLEASE ANSWER FOR EACH TOPIC THE QUESTIONS (IN CAPITAL LETTERS)

Bias in computer usage:

1. An online survey was conducted about computer usage.

-LOOKING AT THE MEANS BY WHICH THE SURVEY WAS CONDUCTED (THROUGH COMPUTERS) EXPLAIN WHY THIS STUDY IS BIASED AND THE TYPE OF BIAS PRESENT.

1. As of June 2008, 55% of web browsers (Internet Explorer) in use did not pass the ACID 2 test. Due to the nature of the test, the group consisted mostly of web developers

WHAT TYPE OF BIAS AFFECTED THIS RESEARCH AND HOW SHOULD IT HAVE BEEN PERFORMED BETTER? ----------------------------------------

Politics and voting polls:

predicting the winner in presidential elections: In 1936, Literary Digest, a national magazine of the time, sent out 10 million "straw" ballots asking people to tell them who they planned on voting for in the 1936 presidential election. (They predicted Alf Landon would beat Franklin Delanor Roosevelt 57% to 43%. As it turned out, Roosevelt won 62% to 37%.) Literary Digest used lists of phone numbers, drivers' registrations, and country club memberships to select its sample. But 1936 was the height of the depression. At that time, phones, cars, and country clubs were more often available only to the rich. The economy was the central campaign issue of the election with Roosevelt advocating the New Deal that was attractive to lower-income people, so the opinions of the rich and poor were bound to differ on this issue. As such, their study turned out to be incredibly biased, and ultimately, useless.

Professors biases:

1. Professor Karl Marx at Pugh university was interested to know how politically active college students are so he conducted a survey on election day in all his classes: 75 % students voted on that day

-WHAT KIND OF BIAS DISCREDITED MARXS STUDY?

-ARE THE RESULTS OVERRATED OR UNDERRATED IN YOUR OPPINION? EXPLAIN.

1. Professors asking students to fill a survey rating their satisfaction with the professors performance
2. When a teacher asks the students whether they understand or not during the class
3. A teacher suggested that the best way to survey the amount of swearing within the school is to have a lot of teachers monitoring the halls during the break.

WHAT KIND OF BIAS CAN YOU DETECT IN EACH OF THE SITUATIONS PRESENTED ABOVE?