Chapter 3 Flashcards
Advantages and disadvantages of the mean
Adv : Takes every data value into account
Disadv : Sensitive to every data value
To find the mean from a frequency distribution
• اطلع الميد بوينتس
• اضرب الميد بوينت بالفريكونسي
• اجمع الناتج لكل اللي ضربتهم واقسمها على مجموع الفركونسي
To find the weighted mean
• Multiply the mean by the number of whatever كل سكشن
• Then divide it by the total of students or whatever
The middle value when the original data values are arranged in order of increasing
Median
• It’s not affected by an extreme value
• It’s a resistance measure of the center
Median
The value that occurs with the greatest frequency
Mode
What’s the measure of central tendency that can be used with nominal data?
MODE
Mode in frequency table
The midpoint of the class with greatest frequency
اكبر فريكونسي بالجدول نطلع الميد بوينت حقها واللي هي نجمعهم ونقسم على ٢
The value midway between the maximum and the minimum
Midrange
How to find the midrange?
Maximum + Minimum
Divide by two
Why is the midrange sensitive to extreme?
Because it uses only the maximum and the minimum values
How to find the midrange for frequency table
Lower class limit of first class + Upper class limit of the last class and divide by two
Mean and median are the left of the mode
Skewed to the left
Mean and median are the right of the mode
Skewed to the right
In any data if the mean is higher than the mode then
Skewed to the right
Difference between the maximum data value and the minimum data value
Range
Range in frequency table
The upper boundary of the last class زائد نص - The lower boundary of the smallest class ناقص نص
Measure of variations of values about the mean
The standard deviation
The value if standard deviation is usually
Positive
To find the standard deviation
نربع القيم ونطلع مجموع القيم ومجموع اللي ربعناه
نفتح جذر نضرب عدد القيم بمجموع اللي ربعناهم
ناقص مجموع القيم الاولى تربيع ونقسم على عدد القيم ضرب عدد القيم ناقص واحد
Standard deviation in frequency table
١- اطلع الميد بوينتس
٢- اضرب الميد بوينتس بالفريكونسي واطلع مجموعهم
٣- اضرب الميد بوينتس بنفسها
٤- اللي ضربتهم بنفسهم اضربهم بالفريكونسي اقين واخذ مجموعهم
٥- اللي بحتاجه عدد الفركونسي ونقطة ٢،٤
٦- افتح جذر واضرب مجموع الفركونسي باخر نقطة واربع نقطة ٢ مقسومه على عدد الفركونسي ضرب ناقص واحد منهم
What’s the range rule of thumb ?
( Range over 4 ) where range is max - min
Empirical rule
- 68% = 1 SD
- 95% = 2 SD
- 99.7% = 3 SD
Coefficient of variation
variance over the mean multiply with 100 and then divide by two
The number of standard deviation that a given value x is above or below the mean
Z score
Whenever a value is less than the mean the z score is
Negative
For the ……. the z score between-2 and 2
Ordinary data
To find the z score corresponding:
Mean over the standard deviation
Measures of location. Which divide a set of data into 100 groups with 1% of the values in each group
Percentiles
To find the percentile corresponding :
Number of values less than x over the total number of values multiply with 100
To find the 10th or whatever percentile :
1- اول شيء احط المطلوب قسمة ١٠٠ ضرب عدد القيم
2- اذا طلع لي عدد بالفواصل اعد من البدايه لو ٣ اعد ٣ ارقام واختار الرقم
3- لو طلع عدد كامل احسبه واخذ العدد اللي بعده واطلع ال midway بجمعهم وقسمة على ٢
Measure of location, which divide a set of data into four groups with about 25% of the values in each group
Quartiles
Q2 is the
Median
Interquartile Range ;
Q3 - Q1
Semi-interquartile Range :
Q3 -Q1 over 2
Mid-quartile
Q3+Q1 over 2
10-90 percentile range :
P90 - P10
What’s the 5-number summary
- Q1
- Q2 median
-Q3
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